diff --git a/changelog.d/fix-ssi-spousal-general-exclusion.added.md b/changelog.d/fix-ssi-spousal-general-exclusion.added.md
new file mode 100644
index 00000000000..cb4319c1cfc
--- /dev/null
+++ b/changelog.d/fix-ssi-spousal-general-exclusion.added.md
@@ -0,0 +1 @@
+Added a monthly variable for SSI income deemed from an ineligible spouse and preserved annual inputs.
diff --git a/changelog.d/fix-ssi-spousal-general-exclusion.fixed.md b/changelog.d/fix-ssi-spousal-general-exclusion.fixed.md
new file mode 100644
index 00000000000..b9d84d42efb
--- /dev/null
+++ b/changelog.d/fix-ssi-spousal-general-exclusion.fixed.md
@@ -0,0 +1 @@
+Applied SSI's general income exclusion once across a couple's income, including the claimant's in-kind support, and preserved monthly support changes under spousal deeming.
diff --git a/policyengine_us/tests/core/test_ssi_monthly_ism_properties.py b/policyengine_us/tests/core/test_ssi_monthly_ism_properties.py
index adc208b0f73..263b95b4c82 100644
--- a/policyengine_us/tests/core/test_ssi_monthly_ism_properties.py
+++ b/policyengine_us/tests/core/test_ssi_monthly_ism_properties.py
@@ -514,7 +514,7 @@ def test_couple_food_pmv_uses_payment_rate_and_splits_countable_income(month):
         "ssi_earned_income": zero,
         "ssi_unearned_income": zero,
         "ssi_unearned_income_deemed_from_ineligible_parent": zero,
-        "ssi_income_deemed_from_ineligible_spouse": zero,
+        "ssi_income_deemed_from_ineligible_spouse_monthly": zero,
         "is_ssi_aged_blind_disabled": np.ones(3, dtype=bool),
         "is_child": zero.astype(bool),
     }
diff --git a/policyengine_us/tests/core/test_ssi_spousal_ism_invariants.py b/policyengine_us/tests/core/test_ssi_spousal_ism_invariants.py
new file mode 100644
index 00000000000..a440246ff7d
--- /dev/null
+++ b/policyengine_us/tests/core/test_ssi_spousal_ism_invariants.py
@@ -0,0 +1,353 @@
+"""Check SSI spousal deeming across generated income changes.
+
+One vectorized Simulation per draw shares the read-only system singleton.
+Independent NumPy calculations preserve main's results without ISM and check
+the combined income budget, exclusion bound, and individual payment limit.
+Leaf ISM inputs keep its value fixed while each cash income rises. Separate
+households increase ISM itself, holding the cash incomes and deeming status
+fixed. YAML checks the PMV calculation and worked monthly payments.
+
+These comparisons exercise the Simulation API's monthly and annual input
+conversion, deemed-income decomposition, and payment cap. The existing
+Rest/core Python group collects this file.
+"""
+
+from types import SimpleNamespace
+
+import numpy as np
+from policyengine_core.periods import period as make_period
+from hypothesis import HealthCheck, given, settings
+from hypothesis import strategies as st
+
+from policyengine_us import Simulation
+from policyengine_us.system import system
+
+
+YEAR = 2026
+PERIOD = "2026-01"
+INDIVIDUAL_FBR = 994
+COUPLE_FBR = 1_491
+GENERAL_EXCLUSION = 20
+EARNED_EXCLUSION = 65
+TOLERANCE = 0.01
+
+
+def _countable(earned, unearned):
+    """Apply 416.1112 and 416.1124 to monthly income independently."""
+    unused_general = np.maximum(GENERAL_EXCLUSION - unearned, 0)
+    return (
+        np.maximum(unearned - GENERAL_EXCLUSION, 0)
+        + np.maximum(earned - EARNED_EXCLUSION - unused_general, 0) / 2
+    )
+
+
+def _situation(rows):
+    situation = {
+        plural: {}
+        for plural in (
+            "people",
+            "tax_units",
+            "households",
+            "marital_units",
+            "families",
+            "spm_units",
+        )
+    }
+    for index, (
+        own_earned,
+        own_unearned,
+        spouse_earned,
+        spouse_unearned,
+        ism,
+    ) in enumerate(rows):
+        claimant, spouse = f"c{index}", f"s{index}"
+        situation["people"][claimant] = {
+            "age": {YEAR: 70},
+            "employment_income": {YEAR: own_earned * 12},
+            "pension_income": {YEAR: own_unearned * 12},
+            "ssi_in_kind_support_and_maintenance": {
+                f"{YEAR}-{month:02}": ism if month == 1 else 0 for month in range(1, 13)
+            },
+        }
+        situation["people"][spouse] = {
+            "age": {YEAR: 60},
+            "employment_income": {YEAR: spouse_earned * 12},
+            "pension_income": {YEAR: spouse_unearned * 12},
+        }
+        for plural in (
+            "tax_units",
+            "households",
+            "marital_units",
+            "families",
+            "spm_units",
+        ):
+            situation[plural][f"u{index}"] = {"members": [claimant, spouse]}
+        situation["households"][f"u{index}"]["state_code"] = {YEAR: "TX"}
+    return situation
+
+
+@settings(
+    max_examples=5,
+    deadline=None,
+    derandomize=True,
+    suppress_health_check=[HealthCheck.too_slow],
+)
+@given(
+    rows=st.lists(
+        st.tuples(
+            st.integers(0, 2_500),
+            st.integers(0, 1_200),
+            st.integers(0, 3_500),
+            st.integers(0, 900),
+            st.integers(0, 25_850),
+            st.integers(1, 100_000),
+        ),
+        min_size=3,
+        max_size=3,
+    )
+)
+def test_spousal_ism_preserves_income_and_exclusion_invariants(rows):
+    # The final coordinates give ISM and the income increase in cents.
+    # Fixed rows retain the wage-only defect, spouse unearned income, and
+    # both sides of the claimant's $20 general exclusion.
+    cases = [
+        *rows,
+        (0, 0, 2_000, 0, 25_850, 100),
+        (0, 0, 2_000, 100, 25_850, 100),
+        (0, 19, 497, 0, 100, 1),
+        (0, 20, 498, 0, 100, 1),
+        (0, 21, 496, 0, 100, 1),
+    ]
+    expanded = []
+    for own_earned, own_unearned, spouse_earned, spouse_unearned, cents, step in cases:
+        expanded.append((own_earned, own_unearned, spouse_earned, spouse_unearned, 0))
+        # Keep deeming active as each income coordinate rises. Changing the
+        # generated PMV at the deeming threshold requires separate YAML cases.
+        supported = np.array(
+            [
+                own_earned,
+                own_unearned,
+                max(spouse_earned, 498),
+                spouse_unearned,
+                cents / 100,
+            ],
+            dtype=float,
+        )
+        expanded.append(supported)
+        for coordinate in range(5):
+            increased = supported.copy()
+            increased[coordinate] += step / 100
+            expanded.append(increased)
+
+    simulation = Simulation(situation=_situation(expanded), tax_benefit_system=system)
+    own_earned, own_unearned, spouse_earned, spouse_unearned, ism = np.array(
+        expanded, dtype=float
+    ).T
+    own_countable = _countable(own_earned, own_unearned + ism)
+    combined_countable = _countable(
+        own_earned + spouse_earned, own_unearned + spouse_unearned + ism
+    )
+    applies = spouse_earned + spouse_unearned > COUPLE_FBR - INDIVIDUAL_FBR
+    expected_deemed = np.where(
+        applies, np.maximum(combined_countable - own_countable, 0), 0
+    )
+    expected_countable = own_countable + expected_deemed
+    individual_payment = np.maximum(INDIVIDUAL_FBR - own_countable, 0)
+    expected_payment = np.where(
+        applies,
+        np.maximum(np.minimum(COUPLE_FBR - combined_countable, individual_payment), 0),
+        individual_payment,
+    )
+
+    countable = simulation.calculate("ssi_countable_income", PERIOD)[0::2]
+    deemed = simulation.calculate(
+        "ssi_income_deemed_from_ineligible_spouse_monthly", PERIOD
+    )[0::2]
+    payment = simulation.calculate("ssi", PERIOD)[0::2]
+    cap = simulation.calculate("uncapped_ssi_without_spousal_deeming", PERIOD)[0::2]
+    np.testing.assert_allclose(countable, expected_countable, atol=TOLERANCE)
+    np.testing.assert_allclose(deemed, expected_deemed, atol=TOLERANCE)
+    np.testing.assert_allclose(payment, expected_payment, atol=TOLERANCE)
+    assert np.all(payment <= np.maximum(cap, 0) + TOLERANCE)
+
+    zero_ism_own = _countable(own_earned, own_unearned)
+    zero_ism_couple = _countable(
+        own_earned + spouse_earned, own_unearned + spouse_unearned
+    )
+    zero_ism_deemed = np.where(
+        applies, np.maximum(zero_ism_couple - zero_ism_own, 0), 0
+    )
+    annual_deemed = simulation.calculate(
+        "ssi_income_deemed_from_ineligible_spouse", YEAR
+    )[0::2]
+    np.testing.assert_allclose(
+        annual_deemed, expected_deemed + 11 * zero_ism_deemed, atol=TOLERANCE
+    )
+    # Calculating the annual aggregate cannot replace February's own budget
+    # with one-twelfth of that aggregate.
+    february_deemed = simulation.calculate(
+        "ssi_income_deemed_from_ineligible_spouse_monthly", f"{YEAR}-02"
+    )[0::2]
+    np.testing.assert_allclose(february_deemed, zero_ism_deemed, atol=TOLERANCE)
+
+    # Freeze main's no-ISM difference formula independently of current
+    # countable or deemed outputs, including its below-threshold path.
+    no_ism = np.arange(0, len(expanded), 7)
+    original_own = _countable(own_earned[no_ism], own_unearned[no_ism])
+    original_couple = _countable(
+        own_earned[no_ism] + spouse_earned[no_ism],
+        own_unearned[no_ism] + spouse_unearned[no_ism],
+    )
+    original_deemed = np.where(
+        applies[no_ism], np.maximum(original_couple - original_own, 0), 0
+    )
+    original_countable = original_own + original_deemed
+    original_alone = INDIVIDUAL_FBR - original_own
+    original_payment = np.maximum(
+        np.where(
+            applies[no_ism],
+            np.minimum(COUPLE_FBR - original_countable, original_alone),
+            original_alone,
+        ),
+        0,
+    )
+    np.testing.assert_allclose(deemed[no_ism], original_deemed, atol=TOLERANCE)
+    np.testing.assert_allclose(
+        annual_deemed[no_ism], 12 * original_deemed, atol=TOLERANCE
+    )
+    np.testing.assert_allclose(countable[no_ism], original_countable, atol=TOLERANCE)
+    np.testing.assert_allclose(payment[no_ism], original_payment, atol=TOLERANCE)
+
+    supported_countable = countable.reshape(len(cases), 7)[:, 1:]
+    assert np.all(supported_countable[:, 1:] >= supported_countable[:, :1] - TOLERANCE)
+
+    # Remove only the general exclusion from an independent couple budget.
+    # Retain the $65 earned exclusion and one-half earned-income disregard.
+    without_general = (
+        own_unearned
+        + spouse_unearned
+        + ism
+        + np.maximum(own_earned + spouse_earned - EARNED_EXCLUSION, 0) / 2
+    )
+    supported = np.ones(len(expanded), dtype=bool)
+    supported[no_ism] = False
+    general_reduction = without_general[supported] - countable[supported]
+    assert np.all(general_reduction >= -TOLERANCE)
+    assert np.all(general_reduction <= GENERAL_EXCLUSION + TOLERANCE)
+
+
+def test_legacy_annual_override_replaces_cached_monthly_budgets():
+    simulation = Simulation(
+        situation=_situation([(0, 0, 2_000, 0, 258.50)]),
+        tax_benefit_system=system,
+    )
+    monthly_name = "ssi_income_deemed_from_ineligible_spouse_monthly"
+    annual_name = "ssi_income_deemed_from_ineligible_spouse"
+    # January counts $258.50 ISM; February counts none. Annual deeming sums
+    # $967.50 + 11 * $957.50 = $11,500 without averaging the ISM correction.
+    np.testing.assert_allclose(
+        simulation.calculate(monthly_name, PERIOD), [967.50, 0], atol=TOLERANCE
+    )
+    np.testing.assert_allclose(
+        simulation.calculate(annual_name, YEAR), [11_500, 0], atol=TOLERANCE
+    )
+
+    # An explicit legacy $2,160 annual input supplies $180 in every month,
+    # including months the parent simulation already calculated.
+    branch = simulation.get_branch("annual_deemed_override")
+    branch.set_input(annual_name, YEAR, [2_160, 0])
+    for month in (PERIOD, f"{YEAR}-02"):
+        np.testing.assert_allclose(
+            branch.calculate(monthly_name, month), [180, 0], atol=TOLERANCE
+        )
+    # An explicit zero overrides calculated deeming as an amount, too.
+    zero_branch = simulation.get_branch("zero_annual_deemed_override")
+    zero_branch.set_input(annual_name, YEAR, [0, 0])
+    np.testing.assert_array_equal(zero_branch.calculate(monthly_name, PERIOD), [0, 0])
+    np.testing.assert_allclose(
+        simulation.calculate(monthly_name, PERIOD), [967.50, 0], atol=TOLERANCE
+    )
+    np.testing.assert_allclose(
+        simulation.calculate(monthly_name, f"{YEAR}-02"), [957.50, 0], atol=TOLERANCE
+    )
+
+
+def test_legacy_annual_override_replaces_cached_ineligible_parent_test():
+    # YAML supplies its inputs before any calculation, so it cannot show that
+    # a branch drops a parent test the simulation calculated earlier.
+    people = {
+        "parent": {
+            "age": {YEAR: 45},
+            "is_tax_unit_head": {YEAR: True},
+            "own_children_in_household": {YEAR: 1},
+            "meets_ssi_disability_criteria": {YEAR: True},
+        },
+        "spouse": {
+            "age": {YEAR: 45},
+            "is_tax_unit_spouse": {YEAR: True},
+            "own_children_in_household": {YEAR: 1},
+            "employment_income": {YEAR: 12_000},
+        },
+        "child": {
+            "age": {YEAR: 10},
+            "is_tax_unit_dependent": {YEAR: True},
+            "meets_ssi_disability_criteria": {YEAR: True},
+        },
+    }
+    everyone = {"members": list(people)}
+    situation = {
+        "people": people,
+        "tax_units": {"tax_unit": everyone},
+        "families": {"family": everyone},
+        "spm_units": {"spm_unit": everyone},
+        "households": {"household": {**everyone, "state_code": {YEAR: "OH"}}},
+        "marital_units": {
+            "parents": {"members": ["parent", "spouse"]},
+            "child": {"members": ["child"]},
+        },
+    }
+    simulation = Simulation(situation=situation, tax_benefit_system=system)
+    flag = "is_ssi_ineligible_parent"
+    # The spouse's wages deem ($12,000 - $240 - $780) / 2 = $5,490, within the
+    # couple rate of $1,491 * 12 = $17,892, so the disabled parent passes.
+    np.testing.assert_array_equal(
+        simulation.calculate(flag, YEAR), [False, True, False]
+    )
+    # A supplied $18,000 exceeds $17,892 and fails the parent on the branch.
+    branch = simulation.get_branch("annual_deemed_override_for_parent_test")
+    branch.set_input("ssi_income_deemed_from_ineligible_spouse", YEAR, [18_000, 0, 0])
+    np.testing.assert_array_equal(branch.calculate(flag, YEAR), [True, True, False])
+    np.testing.assert_array_equal(
+        simulation.calculate(flag, YEAR), [False, True, False]
+    )
+
+
+def test_annual_input_adapter_honors_dated_legacy_abolition():
+    # Exercise the input adapter without constructing another policy system.
+    # Core checks abolition at the requested month before period conversion.
+    from policyengine_us.variables.gov.ssa.ssi.eligibility.income._annual_input import (
+        annual_input,
+    )
+
+    name = "ssi_income_deemed_from_ineligible_spouse"
+
+    class Parameters:
+        def __call__(self, period):
+            return SimpleNamespace(
+                gov=SimpleNamespace(abolitions={name: period.start.month >= 7})
+            )
+
+    holder = SimpleNamespace(
+        variable=SimpleNamespace(is_neutralized=False, definition_period="year"),
+        get_known_branch_periods=lambda: [],
+        _record_store=lambda period, sequence_number: None,
+    )
+    simulation = SimpleNamespace(
+        tax_benefit_system=SimpleNamespace(parameters=Parameters()),
+        get_holder=lambda variable: holder,
+        _user_input_keys=set(),
+        _get_visible_branch_names=lambda: [],
+    )
+    person = SimpleNamespace(simulation=simulation)
+    assert annual_input(person, make_period("2026-01"), name) is None
+    assert annual_input(person, make_period("2026-07"), name) == 0
diff --git a/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.yaml b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.yaml
index 9b620bcd8d0..c3525434547 100644
--- a/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.yaml
@@ -305,3 +305,39 @@
     # Couple: (24,204 / 12 - 20 - 65) x 0.5 x 12 = (2,017 - 85) x 6 = 11,592.
     # Alone: 0. Deemed: 11,592 - 0 = 11,592.
     ssi_income_deemed_from_ineligible_spouse: [0, 0, 11_592, 0]
+
+# SSA includes claimant ISM in the couple's unearned income and applies
+# one general exclusion (POMS SI 01320.150 B.1.a and SI 01320.400 B.1.e).
+# https://secure.ssa.gov/poms.nsf/lnx/0501320150
+# https://secure.ssa.gov/poms.nsf/lnx/0501320400
+- name: Outside shelter support uses the general exclusion once with spouse wages.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        employment_income: 2_000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # 2026 rates: individual $994, couple $1,491; PMV = $1,491 / 6 + $10.
+    # Couple: ($258.50 - $20) + ($2,000 - $65) / 2 = $1,206.
+    # Alone: $258.50 - $20 = $238.50; deemed: $1,206 - $238.50 = $967.50.
+    # Payment: min($1,491 - $1,206, $994 - $994 / 3) = $285.
+    ssi_in_kind_support_and_maintenance: [258.50, 0]
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967.50, 0]
+    ssi_countable_income: [1_206, 0]
+    uncapped_ssi_without_spousal_deeming: [662.67, 0]
+    ssi: [285, 0]
diff --git a/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse_monthly.yaml b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse_monthly.yaml
new file mode 100644
index 00000000000..2257be84a6c
--- /dev/null
+++ b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse_monthly.yaml
@@ -0,0 +1,492 @@
+# SSA includes claimant ISM in combined unearned income before applying
+# one general exclusion (POMS SI 01320.150 B.1.a and SI 01320.400 B.1.e).
+# https://secure.ssa.gov/poms.nsf/lnx/0501320150
+# https://secure.ssa.gov/poms.nsf/lnx/0501320400
+
+- name: Claimant cash unearned income shares one exclusion with shelter support.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 100 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 100 + 0 + 258.5; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $1306; alone: $338.5; deemed: $1306 - $338.5 = $967.5.
+    # SSI: min($1,491 - $1306, $562.6667) = $185.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967.5, 0]
+    ssi_countable_income: [1306, 0]
+    ssi: [185, 0]
+
+- name: Spouse unearned income shares one exclusion with claimant shelter support.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        pension_income: 700 * 12
+        employment_income: 0 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 700 + 258.5; earned: 0 + 0.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $938.5; alone: $238.5; deemed: $938.5 - $238.5 = $700.
+    # SSI: min($1,491 - $938.5, $662.6667) = $552.5.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [700, 0]
+    ssi_countable_income: [938.5, 0]
+    ssi: [552.5, 0]
+
+- name: Mixed spouse income shares one exclusion with claimant shelter support.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        pension_income: 100 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 100 + 258.5; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $1306; alone: $238.5; deemed: $1306 - $238.5 = $1067.5.
+    # SSI: min($1,491 - $1306, $662.6667) = $185.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [1067.5, 0]
+    ssi_countable_income: [1306, 0]
+    ssi: [185, 0]
+
+- name: Cash income without shelter support preserves wages-only deeming.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: false
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 0 + 0; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $957.5; alone: $0; deemed: $957.5 - $0 = $957.5.
+    # SSI: min($1,491 - $957.5, $994.0000) = $533.5.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [957.5, 0]
+    ssi_countable_income: [957.5, 0]
+    ssi: [533.5, 0]
+
+- name: Cash income without shelter support preserves unearned-only deeming.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: false
+      spouse:
+        age: 60
+        pension_income: 700 * 12
+        employment_income: 0 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 700 + 0; earned: 0 + 0.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $680; alone: $0; deemed: $680 - $0 = $680.
+    # SSI: min($1,491 - $680, $994.0000) = $811.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [680, 0]
+    ssi_countable_income: [680, 0]
+    ssi: [811, 0]
+
+- name: Cash income without shelter support preserves mixed-income deeming.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 100 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: false
+      spouse:
+        age: 60
+        pension_income: 100 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 100 + 100 + 0; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $1147.5; alone: $80; deemed: $1147.5 - $80 = $1067.5.
+    # SSI: min($1,491 - $1147.5, $914.0000) = $343.5.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [1067.5, 0]
+    ssi_countable_income: [1147.5, 0]
+    ssi: [343.5, 0]
+
+- name: Shelter support below the general exclusion leaves one dollar for wages.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+        ssi_shelter_support_value: 19
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 0 + 19; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $967; alone: $0; deemed: $967 - $0 = $967.
+    # SSI: min($1,491 - $967, $994.0000) = $524.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967, 0]
+    ssi_countable_income: [967, 0]
+    ssi: [524, 0]
+
+- name: Shelter support at the general exclusion leaves none for wages.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+        ssi_shelter_support_value: 20
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 0 + 20; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $967.5; alone: $0; deemed: $967.5 - $0 = $967.5.
+    # SSI: min($1,491 - $967.5, $994.0000) = $523.5.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967.5, 0]
+    ssi_countable_income: [967.5, 0]
+    ssi: [523.5, 0]
+
+- name: Shelter support above the general exclusion adds countable unearned income.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+        ssi_shelter_support_value: 21
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 0 + 21; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $968.5; alone: $1; deemed: $968.5 - $1 = $967.5.
+    # SSI: min($1,491 - $968.5, $993.0000) = $522.5.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967.5, 0]
+    ssi_countable_income: [968.5, 0]
+    ssi: [522.5, 0]
+
+- name: Claimant cash below the general exclusion shares the remainder with support.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 19 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 19 + 0 + 258.5; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $1225; alone: $257.5; deemed: $1225 - $257.5 = $967.5.
+    # SSI: min($1,491 - $1225, $643.6667) = $266.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967.5, 0]
+    ssi_countable_income: [1225, 0]
+    ssi: [266, 0]
+
+- name: Claimant cash at the general exclusion leaves none for support.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 20 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 20 + 0 + 258.5; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $1226; alone: $258.5; deemed: $1226 - $258.5 = $967.5.
+    # SSI: min($1,491 - $1226, $642.6667) = $265.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967.5, 0]
+    ssi_countable_income: [1226, 0]
+    ssi: [265, 0]
+
+- name: Claimant cash above the general exclusion leaves none for support.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 21 * 12
+        employment_income: 0 * 12
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 21 + 0 + 258.5; earned: 0 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $1227; alone: $259.5; deemed: $1227 - $259.5 = $967.5.
+    # SSI: min($1,491 - $1227, $641.6667) = $264.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [967.5, 0]
+    ssi_countable_income: [1227, 0]
+    ssi: [264, 0]
+
+- name: Claimant earnings share the earned exclusion across the couple.
+  period: 2026-01
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        pension_income: 0 * 12
+        employment_income: 100 * 12
+        ssi_receives_outside_shelter_support: true
+      spouse:
+        age: 60
+        pension_income: 0 * 12
+        employment_income: 2000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Unearned: 0 + 0 + 258.5; earned: 100 + 2000.
+    # Subtract $20 from unearned, carry any remainder to earnings,
+    # then subtract $65 from earnings and count half the remainder.
+    # Couple: $1256; alone: $256; deemed: $1256 - $256 = $1000.
+    # SSI: min($1,491 - $1256, $645.1667) = $235.
+    ssi_income_deemed_from_ineligible_spouse_monthly: [1000, 0]
+    ssi_countable_income: [1256, 0]
+    ssi: [235, 0]
+
+- name: Shelter support in July leaves other months unchanged and annual deeming sums the months.
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      claimant:
+        age: 70
+        ssi_receives_outside_shelter_support:
+          2026-01: false
+          2026-07: true
+          2026-08: false
+      spouse:
+        age: 60
+        employment_income: 2_000 * 12
+    tax_units:
+      couple:
+        members: [claimant, spouse]
+    marital_units:
+      couple:
+        members: [claimant, spouse]
+    households:
+      home:
+        members: [claimant, spouse]
+        state_code: FL
+  output:
+    # Without support: ($2,000 - $20 - $65) / 2 = $957.50 deemed;
+    # SSI = $1,491 - $957.50 = $533.50.
+    # July: ($258.50 - $20) + ($2,000 - $65) / 2 = $1,206 countable;
+    # deemed = $1,206 - $238.50 = $967.50; SSI = $285.
+    # Annual deemed: 11 x $957.50 + $967.50 = $11,500.
+    # Annual SSI: 11 x $533.50 + $285 = $6,153.50.
+    ssi_income_deemed_from_ineligible_spouse_monthly:
+      2026-01: [957.50, 0]
+      2026-07: [967.50, 0]
+    ssi_income_deemed_from_ineligible_spouse: [11_500, 0]
+    ssi_countable_income:
+      2026-01: [957.50, 0]
+      2026-07: [1_206, 0]
+    ssi:
+      2026-01: [533.50, 0]
+      2026-07: [285, 0]
+      2026: [6_153.50, 0]
diff --git a/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.yaml b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.yaml
index 633a5341e0b..83bdf6c68d4 100644
--- a/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.yaml
@@ -1013,3 +1013,95 @@
     is_ssi_ineligible_parent: [false, false, false]
     ssi_unearned_income_deemed_from_ineligible_parent: [0, 0, 0]
     ssi: [0, 0, 11_928]
+
+# A disabled parent with no cash income receives shelter support from outside the
+# household, and the spouse earns 24,000. While the spouse's income is deemed, SSA
+# values that support at 1,491 / 6 + 10 = 258.50 a month and counts it with the
+# couple's unearned income (POMS SI 01320.150 B.1.a), so one 20 exclusion applies:
+# (258.50 - 20) + (2,000 - 65) / 2 = 1,206, and the deemed amount is 1,206 - 238.50 =
+# 967.50 a month, or 11,610 a year. The parent's SSI is (1,491 - 1,206) x 12 = 3,420.
+# The ineligible-parent test leaves out in-kind support: (24,000 - 240 - 780) / 2 =
+# 11,490 is within 17,892, so the parent stays eligible, and 20 CFR 416.1166(e)(1)
+# deems nothing to the disabled child, whose SSI is 994 x 12 = 11,928.
+- name: Case 28, disabled parent with shelter support and an earning spouse stays eligible.
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      person1:
+        age: 45
+        is_tax_unit_head: true
+        own_children_in_household: 1
+        meets_ssi_disability_criteria: true
+        ssi_receives_outside_shelter_support: true
+      person2:
+        age: 45
+        is_tax_unit_spouse: true
+        own_children_in_household: 1
+        employment_income_before_lsr: 24_000
+      person3:
+        age: 10
+        is_tax_unit_dependent: true
+        meets_ssi_disability_criteria: true
+    tax_units:
+      tax_unit:
+        members: [person1, person2, person3]
+    marital_units:
+      marital_unit1:
+        members: [person1, person2]
+      marital_unit2:
+        members: [person3]
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: OH
+  output:
+    is_ssi_ineligible_parent: [false, true, false]
+    ssi_in_kind_support_and_maintenance: [3_102, 0, 0]
+    ssi_income_deemed_from_ineligible_spouse: [11_610, 0, 0]
+    ssi_unearned_income_deemed_from_ineligible_parent: [0, 0, 0]
+    ssi: [3_420, 0, 11_928]
+
+# A supplied annual deemed amount decides the parent's test. The spouse earns 12,000,
+# which would deem (12,000 - 240 - 780) / 2 = 5,490, but the supplied 18,000 exceeds
+# the couple rate of 1,491 x 12 = 17,892, so both parents are ineligible parents. The
+# parents' 5,490 after exclusions falls short of the couple rate that 20 CFR
+# 416.1165(d)(3)(i) allocates to them, so nothing is deemed to the child, whose SSI is
+# 11,928. The parent's countable income of 18,000 / 12 = 1,500 a month exceeds 1,491,
+# so the parent's SSI is 0.
+- name: Case 29, supplied annual spousal deemed income decides the parent's income test.
+  period: 2026
+  absolute_error_margin: 0.01
+  input:
+    people:
+      person1:
+        age: 45
+        is_tax_unit_head: true
+        own_children_in_household: 1
+        meets_ssi_disability_criteria: true
+        ssi_income_deemed_from_ineligible_spouse: 18_000
+      person2:
+        age: 45
+        is_tax_unit_spouse: true
+        own_children_in_household: 1
+        employment_income_before_lsr: 12_000
+      person3:
+        age: 10
+        is_tax_unit_dependent: true
+        meets_ssi_disability_criteria: true
+    tax_units:
+      tax_unit:
+        members: [person1, person2, person3]
+    marital_units:
+      marital_unit1:
+        members: [person1, person2]
+      marital_unit2:
+        members: [person3]
+    households:
+      household:
+        members: [person1, person2, person3]
+        state_code: OH
+  output:
+    is_ssi_ineligible_parent: [true, true, false]
+    ssi_unearned_income_deemed_from_ineligible_parent: [0, 0, 0]
+    ssi: [0, 0, 11_928]
diff --git a/policyengine_us/tests/policy/baseline/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.yaml b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.yaml
index 1fd53696d6e..92f25ec5dd0 100644
--- a/policyengine_us/tests/policy/baseline/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.yaml
@@ -135,17 +135,18 @@
 
 # 2024 Federal benefit rates: $943 individual, $1,415 couple; the deeming
 # threshold is their difference, $472. The spouse in each case below earns
-# $500 a month, so deeming applies, and the model deems
-# ($500 - $20 - $65) / 2 = $207.50.
+# $500 a month, so deeming applies. While food counts as ISM, the
+# claimant uses the general exclusion on ISM and spouse wages contribute
+# ($500 - $65) / 2 = $217.50. Without ISM, wages contribute $207.50.
 # Under 20 CFR 416.420(a) a payment counts food from its second prior income
 # month, and food stops counting on September 30, 2024 (89 FR 21199).
-# SI 01320.400 C.2 computes the individual amount from that budget month, so
-# the limit follows each month's PMV status.
+# Under SI 01320.400 C.2, SSA uses that budget month for the individual
+# computation, including that month's PMV status.
 # Individual PMV: $943 / 3 + $20 = $334.33; less the $20 general exclusion,
 # $314.33 counts, which leaves $943 - $314.33 = $628.67.
 # The model's deeming computation counts the deemed PMV, $1,415 / 6 + $10 =
-# $245.83, less $20, plus $207.50: $1,415 - $433.33 = $981.67, so the lesser
-# is the individual limit.
+# $245.83, less $20, plus $217.50: $1,415 - $443.33 = $971.67.
+# The individual computation still gives the lesser payment.
 # Core stores a plain yearly input in a month case for the year that starts
 # that month, so we key age, earnings and state to 2024 in the month cases.
 
diff --git a/policyengine_us/tests/policy/baseline/gov/states/ok/dhs/ssp/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/ok/dhs/ssp/integration.yaml
index 95731b1700c..9aad62d1ba4 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/ok/dhs/ssp/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/ok/dhs/ssp/integration.yaml
@@ -476,13 +476,15 @@
     # the ineligible spouse's own 994 / 3 + 20 = 351.33 is excluded by
     # 317:35-5-42(l)(12).
     ssi_in_kind_support_and_maintenance: [258.5, 351.33]
-    # Federal: 1_491 - (258.50 - 20 + 700 - 20) = 572.50 (the deeming
-    # computation applies the $20 exclusion twice; issue 10243).
-    ssi: [572.5, 0]
-    # Combined: 258.50 + 700 - 20 + 572.50 = 1_511, the same as when only
-    # person1 receives the support; min(1_532 - 1_511, 40) = 21.
-    ok_ssp_countable_income: [1_511, 1_511]
-    ok_ssp: [21, 0]
+    # Federal: SSA adds the claimant's support to the spouse's 700 and applies
+    # one $20 exclusion (POMS SI 01320.150 B.1.a, SI 01320.400 B.1.e):
+    # 1_491 - (258.50 + 700 - 20) = 552.50, below the individual-only limit
+    # of 994 - (351.33 - 20) = 662.67 (20 CFR 416.1163(e)(2)).
+    ssi: [552.5, 0]
+    # Combined: 258.50 + 700 - 20 + 552.50 = 1_491, the same as when only
+    # person1 receives the support; min(1_532 - 1_491, 40) = 40.
+    ok_ssp_countable_income: [1_491, 1_491]
+    ok_ssp: [40, 0]
 
 - name: Case 17, eligible couple's shared in-kind support and maintenance counts once.
   period: 2026-01
diff --git a/policyengine_us/variables/gov/ssa/ssi/_ssi_state_supplement.py b/policyengine_us/variables/gov/ssa/ssi/_ssi_state_supplement.py
index caf109a7574..3c1d3cf0a43 100644
--- a/policyengine_us/variables/gov/ssa/ssi/_ssi_state_supplement.py
+++ b/policyengine_us/variables/gov/ssa/ssi/_ssi_state_supplement.py
@@ -49,7 +49,7 @@ def ssi_state_supplement(
     payment = max_(standard - excess, 0)
 
     deeming = person("is_ssi_spousal_deeming_applies", period.this_year)
-    deemed = person("ssi_income_deemed_from_ineligible_spouse", period)
+    deemed = person("ssi_income_deemed_from_ineligible_spouse_monthly", period)
     own_income = max_(countable - deemed, 0)
     ssi = parameters(period).gov.ssa.ssi
     federal_la = person("ssi_federal_living_arrangement", period)
diff --git a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/_annual_input.py b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/_annual_input.py
new file mode 100644
index 00000000000..98c59d5b951
--- /dev/null
+++ b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/_annual_input.py
@@ -0,0 +1,34 @@
+"""Read legacy annual inputs without averaging calculated monthly budgets."""
+
+from policyengine_core.data_storage.store_history import next_sequence_number
+
+from policyengine_us.model_api import has_input_for_period
+
+
+def annual_input(person, period, name):
+    """Return a supplied annual input, or None to calculate the monthly budget.
+
+    A calculated annual aggregate must never replace a month's own budget.
+    Recording the input-presence dependency also lets Core invalidate cached
+    monthly budgets when a branch supplies its first annual override later.
+    """
+    simulation = person.simulation
+    holder = simulation.get_holder(name)
+    # Core records dependencies by store order. It has no public method for
+    # this record, so the adapter calls the holder's private one.
+    holder._record_store(period.this_year, next_sequence_number())
+
+    # Monthly readers retain dated abolition switches on the annual name.
+    if simulation.tax_benefit_system.parameters(period).gov.abolitions[name]:
+        return 0
+
+    abolished = simulation.tax_benefit_system.parameters(
+        period.this_year
+    ).gov.abolitions[name]
+    if (
+        holder.variable.is_neutralized
+        or abolished
+        or has_input_for_period(simulation, name, period.this_year)
+    ):
+        return person(name, period.this_year)
+    return None
diff --git a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/README.md b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/README.md
index 520cf7efbcd..50df6338ffd 100644
--- a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/README.md
+++ b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/README.md
@@ -29,10 +29,13 @@ The implementation follows these steps according to the regulations:
 4. **Calculate combined countable income** (§416.1163(d)(2))
 
    - Combine the eligible individual's and ineligible spouse's incomes
-   - Apply all appropriate income exclusions to the combined income
+   - Count the eligible individual's in-kind support and maintenance (ISM) as unearned income, valued at one-sixth of the couple FBR plus $10 at most ([POMS SI 01320.150 B.1.a](https://secure.ssa.gov/poms.nsf/lnx/0501320150))
+   - Apply all appropriate income exclusions to the combined income, including one $20 general exclusion ([SI 01320.400 B.1.e](https://secure.ssa.gov/poms.nsf/lnx/0501320400))
 
 5. **Calculate deemed income amount**
    - The deemed amount is the difference between the combined countable income and the individual's countable income
+   - `ssi_income_deemed_from_ineligible_spouse_monthly` computes it each month, with the individual's ISM in both budgets, and `ssi_income_deemed_from_ineligible_spouse` sums the months
+   - `is_ssi_ineligible_parent` tests a parent's own income without ISM, so it reads a deemed amount without ISM (`_deemed_income_without_ism.py`)
 
 6. **Limit the benefit to the amount without deeming** (§416.1163(e)(2))
    - We compare the couple computation with the individual Federal benefit rate less the individual's own countable income (`uncapped_ssi_without_spousal_deeming`) and apply the lesser amount in `uncapped_ssi` before the zero floor.
diff --git a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/_deemed_income_without_ism.py b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/_deemed_income_without_ism.py
new file mode 100644
index 00000000000..b304a8ec387
--- /dev/null
+++ b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/_deemed_income_without_ism.py
@@ -0,0 +1,46 @@
+"""Annual spousal deemed income for a reader that leaves out in-kind support."""
+
+from policyengine_us.model_api import *
+from policyengine_us.variables.gov.ssa.ssi.eligibility.income._annual_input import (
+    annual_input,
+)
+from policyengine_us.variables.gov.ssa.ssi.eligibility.income._apply_ssi_exclusions import (
+    _apply_ssi_exclusions,
+)
+
+
+def ssi_income_deemed_from_ineligible_spouse_without_ism(person, period, parameters):
+    """Return a year's income deemed from an ineligible spouse without the
+    claimant's in-kind support and maintenance (ISM).
+
+    is_ssi_ineligible_parent tests a parent's own income without ISM, since
+    ISM depends on the living arrangement and the living arrangement depends
+    on that test. This amount puts the spouse's deemed income on the same
+    basis. ssi_income_deemed_from_ineligible_spouse adds the claimant's ISM to
+    both budgets (POMS SI 01320.150 B.1.a), so reading it there would close
+    that loop. A supplied annual ssi_income_deemed_from_ineligible_spouse, or
+    its neutralization or abolition, still takes precedence.
+    """
+    supplied = annual_input(person, period, "ssi_income_deemed_from_ineligible_spouse")
+    if supplied is not None:
+        return supplied
+
+    deeming_applies = person("is_ssi_spousal_deeming_applies", period)
+    own_earned = person("ssi_earned_income", period)
+    own_unearned = person("ssi_unearned_income", period)
+    spouse_earned = person("ssi_earned_income_deemed_from_ineligible_spouse", period)
+    spouse_unearned = person(
+        "ssi_unearned_income_deemed_from_ineligible_spouse", period
+    )
+    # 20 CFR 416.1163(d)(2): combined countable income less the claimant's own.
+    alone_countable = _apply_ssi_exclusions(
+        own_earned, own_unearned, parameters, period
+    )
+    couple_countable = _apply_ssi_exclusions(
+        own_earned + spouse_earned,
+        own_unearned + spouse_unearned,
+        parameters,
+        period,
+    )
+    deemed = deeming_applies * max_(0, couple_countable - alone_countable)
+    return where(person("is_ssi_aged_blind_disabled", period), deemed, 0)
diff --git a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.py b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.py
index 9e81894574e..996ca6666ef 100644
--- a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.py
+++ b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.py
@@ -1,9 +1,4 @@
-# policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse.py
-
 from policyengine_us.model_api import *
-from policyengine_us.variables.gov.ssa.ssi.eligibility.income._apply_ssi_exclusions import (
-    _apply_ssi_exclusions,
-)
 
 
 class ssi_income_deemed_from_ineligible_spouse(Variable):
@@ -12,47 +7,13 @@ class ssi_income_deemed_from_ineligible_spouse(Variable):
     label = "SSI income (deemed from ineligible spouse)"
     definition_period = YEAR
     reference = "https://www.law.cornell.edu/cfr/text/20/416.1163"
-    documentation = """
-    Spousal deeming: 
-      1) If leftover spouse income <= (coupleFBR - indivFBR), then 0 is deemed.
-      2) Otherwise, spouse's deemed = (couple combined countable) - (individual alone countable).
-         This yields 816 for 1986 Example 3 and 12000 for the 2025 test.
-    """
+    documentation = (
+        "Annual income deemed from an ineligible spouse, summing each month's "
+        "combined countable income less the claimant's own countable income. "
+        "Supplied annual amounts retain their annual units."
+    )
     defined_for = "is_ssi_aged_blind_disabled"
     unit = USD
 
     def formula(person, period, parameters):
-        # 1. Check if spousal deeming applies (avoids duplicating threshold logic)
-        deeming_applies = person("is_ssi_spousal_deeming_applies", period)
-
-        # 2. If deeming applies, calculate deemed amount using "difference" approach:
-        #    (couple combined countable) - (individual alone countable)
-
-        # Get spouse's leftover income (post-child allocations)
-        spouse_earned = person(
-            "ssi_earned_income_deemed_from_ineligible_spouse", period
-        )
-        spouse_unearned = person(
-            "ssi_unearned_income_deemed_from_ineligible_spouse", period
-        )
-
-        # Get individual's own income
-        individual_earned = person("ssi_earned_income", period)
-        individual_unearned = person("ssi_unearned_income", period)
-
-        # Calculate individual's countable income (alone)
-        alone_countable = _apply_ssi_exclusions(
-            individual_earned, individual_unearned, parameters, period
-        )
-
-        # Calculate couple's combined countable income
-        couple_countable = _apply_ssi_exclusions(
-            individual_earned + spouse_earned,
-            individual_unearned + spouse_unearned,
-            parameters,
-            period,
-        )
-
-        # Deemed amount is the difference (only when deeming applies)
-        deemed_amount = max_(0, couple_countable - alone_countable)
-        return deeming_applies * deemed_amount
+        return add(person, period, ["ssi_income_deemed_from_ineligible_spouse_monthly"])
diff --git a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse_monthly.py b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse_monthly.py
new file mode 100644
index 00000000000..60cf5f0b7dd
--- /dev/null
+++ b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/deemed/from_ineligible_spouse/ssi_income_deemed_from_ineligible_spouse_monthly.py
@@ -0,0 +1,63 @@
+from policyengine_us.model_api import *
+from policyengine_us.variables.gov.ssa.ssi.eligibility.income._annual_input import (
+    annual_input,
+)
+from policyengine_us.variables.gov.ssa.ssi.eligibility.income._apply_ssi_exclusions import (
+    _apply_ssi_exclusions_monthly,
+)
+
+
+class ssi_income_deemed_from_ineligible_spouse_monthly(Variable):
+    value_type = float
+    entity = Person
+    label = "Monthly SSI income deemed from an ineligible spouse"
+    definition_period = MONTH
+    unit = USD
+    reference = (
+        "https://www.ssa.gov/OP_Home/cfr20/416/416-1163.htm",
+        "https://secure.ssa.gov/poms.nsf/lnx/0501320150",
+        "https://secure.ssa.gov/poms.nsf/lnx/0501320400",
+    )
+    documentation = (
+        "Monthly combined countable income less the claimant's own countable "
+        "income when spousal deeming applies. Both budgets include the "
+        "claimant's in-kind support before applying one general exclusion. "
+        "Supplied legacy annual deemed income takes precedence."
+    )
+
+    def formula(person, period, parameters):
+        supplied = annual_input(
+            person, period, "ssi_income_deemed_from_ineligible_spouse"
+        )
+        if supplied is not None:
+            return supplied / MONTHS_IN_YEAR
+
+        deeming_applies = person("is_ssi_spousal_deeming_applies", period.this_year)
+        spouse_earned = person(
+            "ssi_earned_income_deemed_from_ineligible_spouse", period
+        )
+        spouse_unearned = person(
+            "ssi_unearned_income_deemed_from_ineligible_spouse", period
+        )
+        individual_earned = person("ssi_earned_income", period)
+        # SSA counts claimant ISM in combined unearned income under
+        # SI 01320.150 B.1.a. Include it in both budgets so their difference
+        # adds no second general exclusion when ssi_countable_income counts ISM.
+        individual_unearned = person("ssi_unearned_income", period) + person(
+            "ssi_in_kind_support_and_maintenance", period
+        )
+        alone_countable = _apply_ssi_exclusions_monthly(
+            individual_earned, individual_unearned, parameters, period
+        )
+        couple_countable = _apply_ssi_exclusions_monthly(
+            individual_earned + spouse_earned,
+            individual_unearned + spouse_unearned,
+            parameters,
+            period,
+        )
+        deemed_amount = max_(0, couple_countable - alone_countable)
+        return where(
+            person("is_ssi_aged_blind_disabled", period),
+            deeming_applies * deemed_amount,
+            0,
+        )
diff --git a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/ssi_countable_income.py b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/ssi_countable_income.py
index 264a0894ba3..b97ef9062c7 100644
--- a/policyengine_us/variables/gov/ssa/ssi/eligibility/income/ssi_countable_income.py
+++ b/policyengine_us/variables/gov/ssa/ssi/eligibility/income/ssi_countable_income.py
@@ -74,7 +74,9 @@ def formula(person, period, parameters):
         both_eligible = person("ssi_couple_computation_applies", period)
 
         # Add spousal deemed income (only relevant when one spouse is ineligible)
-        spousal_deemed = person("ssi_income_deemed_from_ineligible_spouse", period)
+        spousal_deemed = person(
+            "ssi_income_deemed_from_ineligible_spouse_monthly", period
+        )
 
         # People who are not aged, blind, or disabled have no countable income
         # of their own; a spouse's income is deemed to the other spouse
diff --git a/policyengine_us/variables/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.py b/policyengine_us/variables/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.py
index cbcd056ce88..4b172a31db3 100644
--- a/policyengine_us/variables/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.py
+++ b/policyengine_us/variables/gov/ssa/ssi/eligibility/status/is_ssi_ineligible_parent.py
@@ -2,6 +2,9 @@
 from policyengine_us.variables.gov.ssa.ssi.eligibility.income._apply_ssi_exclusions import (
     _apply_ssi_exclusions,
 )
+from policyengine_us.variables.gov.ssa.ssi.eligibility.income.deemed.from_ineligible_spouse._deemed_income_without_ism import (
+    ssi_income_deemed_from_ineligible_spouse_without_ism,
+)
 from policyengine_us.variables.gov.ssa.ssi.eligibility.resources.deemed._ssi_spouses import (
     _ssi_established_spouse_indices,
 )
@@ -43,13 +46,16 @@ def formula(person, period, parameters):
         unearned = person("ssi_unearned_income", period)
         # A joint claim tests the couple's income. Otherwise 416.1163(d)(2) adds
         # what remains of an ineligible spouse's income after the allocations
-        # for ineligible children in 416.1163(b).
+        # for ineligible children in 416.1163(b). Like the parent's own income,
+        # the deemed amount leaves out in-kind support and maintenance.
         countable_income = _apply_ssi_exclusions(
             where(joint_claim, person.marital_unit.sum(earned), earned),
             where(joint_claim, person.marital_unit.sum(unearned), unearned),
             parameters,
             period,
-        ) + person("ssi_income_deemed_from_ineligible_spouse", period)
+        ) + ssi_income_deemed_from_ineligible_spouse_without_ism(
+            person, period, parameters
+        )
         p = parameters(period).gov.ssa.ssi
         benefit_rate = where(
             joint_claim | person("is_ssi_spousal_deeming_applies", period),
diff --git a/policyengine_us/variables/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.py b/policyengine_us/variables/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.py
index 8d54fba0db3..62e324c1b4d 100644
--- a/policyengine_us/variables/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.py
+++ b/policyengine_us/variables/gov/ssa/ssi/uncapped_ssi_without_spousal_deeming.py
@@ -39,7 +39,7 @@ def formula(person, period, parameters):
         # Countable income adds income deemed from an ineligible spouse to the
         # person's own countable income; remove it.
         own_countable_income = person("ssi_countable_income", period) - person(
-            "ssi_income_deemed_from_ineligible_spouse", period
+            "ssi_income_deemed_from_ineligible_spouse_monthly", period
         )
         # SSA applies the regular individual PMV to this individual
         # computation (POMS SI 01320.150 B.1.b and SI 01320.400 C.2).
diff --git a/policyengine_us/variables/gov/states/ca/cdss/capi/ca_capi_person.py b/policyengine_us/variables/gov/states/ca/cdss/capi/ca_capi_person.py
index 1c3ebaeaa25..caddf021c70 100644
--- a/policyengine_us/variables/gov/states/ca/cdss/capi/ca_capi_person.py
+++ b/policyengine_us/variables/gov/states/ca/cdss/capi/ca_capi_person.py
@@ -53,7 +53,9 @@ def formula(person, period, parameters):
             separated, own_alone, person("ssi_countable_income", period)
         )
         payment_standard = person("ca_capi_payment_standard", period)
-        deemed_income = person("ssi_income_deemed_from_ineligible_spouse", period)
+        deemed_income = person(
+            "ssi_income_deemed_from_ineligible_spouse_monthly", period
+        )
         own_income = max_(countable_income - deemed_income, 0)
         # Deeming needs an ineligible spouse living in the same household
         # (20 CFR 416.1160(a)(1)), so a Title XIX facility resident counts
diff --git a/policyengine_us/variables/gov/states/ky/dcbs/ssp/ky_ssp_countable_income.py b/policyengine_us/variables/gov/states/ky/dcbs/ssp/ky_ssp_countable_income.py
index 217e8fe4deb..3866d6061ea 100644
--- a/policyengine_us/variables/gov/states/ky/dcbs/ssp/ky_ssp_countable_income.py
+++ b/policyengine_us/variables/gov/states/ky/dcbs/ssp/ky_ssp_countable_income.py
@@ -36,7 +36,9 @@ def formula(person, period, parameters):
         personal_countable = unearned + countable_earned
 
         both_eligible = person("ssi_couple_computation_applies", period)
-        spousal_deemed = person("ssi_income_deemed_from_ineligible_spouse", period)
+        spousal_deemed = person(
+            "ssi_income_deemed_from_ineligible_spouse_monthly", period
+        )
         # NOTE: ssi_countable_income now zeroes only people who are not aged,
         # blind or disabled. This keeps SSI's eligibility gate, which changes
         # nothing because KY SSP requires is_ssi_eligible.
diff --git a/policyengine_us/variables/gov/states/md/dhs/fia/paa/md_paa_imputed_federal_ssi.py b/policyengine_us/variables/gov/states/md/dhs/fia/paa/md_paa_imputed_federal_ssi.py
index dae9a715beb..f3e7d87a3f5 100644
--- a/policyengine_us/variables/gov/states/md/dhs/fia/paa/md_paa_imputed_federal_ssi.py
+++ b/policyengine_us/variables/gov/states/md/dhs/fia/paa/md_paa_imputed_federal_ssi.py
@@ -56,7 +56,9 @@ def formula(person, period, parameters):
             in_medical_facility, p.medical_facility, p.individual * vtr_factor
         )
         individual_ssi = individual_rate - countable_income
-        deemed_income = person("ssi_income_deemed_from_ineligible_spouse", period)
+        deemed_income = person(
+            "ssi_income_deemed_from_ineligible_spouse_monthly", period
+        )
         couple_ssi = p.couple * vtr_factor - (countable_income + deemed_income)
         deeming = (
             person("is_ssi_spousal_deeming_applies", period.this_year)
diff --git a/policyengine_us/variables/gov/states/tx/hhsc/ssi_state_supplement/tx_ssi_state_supplement_eligible.py b/policyengine_us/variables/gov/states/tx/hhsc/ssi_state_supplement/tx_ssi_state_supplement_eligible.py
index dbd74169175..fe1fe9cd905 100644
--- a/policyengine_us/variables/gov/states/tx/hhsc/ssi_state_supplement/tx_ssi_state_supplement_eligible.py
+++ b/policyengine_us/variables/gov/states/tx/hhsc/ssi_state_supplement/tx_ssi_state_supplement_eligible.py
@@ -40,7 +40,7 @@ def formula(person, period, parameters):
         p = parameters(period).gov.ssa.ssi
         own_countable_income = max_(
             person("ssi_countable_income", period)
-            - person("ssi_income_deemed_from_ineligible_spouse", period),
+            - person("ssi_income_deemed_from_ineligible_spouse_monthly", period),
             0,
         )
         within_reduced_rate = own_countable_income <= p.amount.medical_facility