diff --git a/changelog.d/cbo-2026-projections-2036.changed.md b/changelog.d/cbo-2026-projections-2036.changed.md
new file mode 100644
index 00000000000..e46b07d2803
--- /dev/null
+++ b/changelog.d/cbo-2026-projections-2036.changed.md
@@ -0,0 +1 @@
+Load CBO's February 2026 projections through 2036 into the SSA, SNAP and HHS upraters, the CPI-W series, the national average wage index and the Social Security payroll cap, growing each from its latest actual (the HHS index from its 2026 value); keep CBO's 2035 CPI-U and chained CPI-U points instead of extrapolating over them and add their 2036 points; and extend the payroll cap after 2036 with the 42 U.S.C. 430(b) fixed-base formula.
diff --git a/policyengine_us/parameters/gov/bls/cpi/c_cpi_u.yaml b/policyengine_us/parameters/gov/bls/cpi/c_cpi_u.yaml
index f9f7cc3021e..851b5f35b38 100644
--- a/policyengine_us/parameters/gov/bls/cpi/c_cpi_u.yaml
+++ b/policyengine_us/parameters/gov/bls/cpi/c_cpi_u.yaml
@@ -332,7 +332,8 @@ values:
   2033-02-01: 210.8 # 2034 value.
   2034-02-01: 214.9 # 2035 value.
   2035-02-01: 219.2 # 2036 value.
-  # Values for 2036-2100 are set programmatically in uprating_extensions.py
+  2036-02-01: 223.5 # 2037 value.
+  # Values for 2037-2100 are set programmatically in uprating_extensions.py
 metadata:
   economy: false
   unit: currency-USD
diff --git a/policyengine_us/parameters/gov/bls/cpi/cpi_u.yaml b/policyengine_us/parameters/gov/bls/cpi/cpi_u.yaml
index 2a76d76e7ec..94d670cb424 100644
--- a/policyengine_us/parameters/gov/bls/cpi/cpi_u.yaml
+++ b/policyengine_us/parameters/gov/bls/cpi/cpi_u.yaml
@@ -1373,7 +1373,8 @@ values:
   2033-02-01: 389.6 # 2034 value.
   2034-02-01: 398.4 # 2035 value.
   2035-02-01: 407.3 # 2036 value.
-  # Values for 2036-2100 are set programmatically in uprating_extensions.py
+  2036-02-01: 416.5 # 2037 value.
+  # Values for 2037-2100 are set programmatically in uprating_extensions.py
 metadata:
   unit: currency-USD
   label: CPI-U
diff --git a/policyengine_us/parameters/gov/bls/cpi/cpi_w.yaml b/policyengine_us/parameters/gov/bls/cpi/cpi_w.yaml
index 70da83e8ba9..b3254cfe304 100644
--- a/policyengine_us/parameters/gov/bls/cpi/cpi_w.yaml
+++ b/policyengine_us/parameters/gov/bls/cpi/cpi_w.yaml
@@ -1402,7 +1402,14 @@ values:
   2034-08-01: 391.234 # 2034Q3: 399.460 * 327.075 / 333.952
   2034-11-01: 393.423 # 2034Q4: 401.695 * 327.075 / 333.952
   2035-02-01: 395.625 # 2035Q1: 403.943 * 327.075 / 333.952
-  # Values for 2036-2100 are set programmatically in uprating_extensions.py
+  2035-05-01: 397.838 # 2035Q2: 406.203 * 327.075 / 333.952
+  2035-08-01: 400.064 # 2035Q3: 408.476 * 327.075 / 333.952
+  2035-11-01: 402.303 # 2035Q4: 410.762 * 327.075 / 333.952
+  2036-02-01: 404.555 # 2036Q1: 413.061 * 327.075 / 333.952
+  2036-05-01: 406.819 # 2036Q2: 415.373 * 327.075 / 333.952
+  2036-08-01: 409.096 # 2036Q3: 417.698 * 327.075 / 333.952
+  2036-11-01: 411.386 # 2036Q4: 420.036 * 327.075 / 333.952
+  # Values for 2037-2100 are set programmatically in uprating_extensions.py
 metadata:
   unit: currency-USD
   label: CPI-W
diff --git a/policyengine_us/parameters/gov/hhs/uprating.yaml b/policyengine_us/parameters/gov/hhs/uprating.yaml
index 7b226f6572e..b7daa2e9dcc 100644
--- a/policyengine_us/parameters/gov/hhs/uprating.yaml
+++ b/policyengine_us/parameters/gov/hhs/uprating.yaml
@@ -1,22 +1,30 @@
 description: The US indexes the federal poverty guidelines according to this schedule, annually updating based on CPI-U in the calendar year.
 values:
   # Actuals: calendar-year average CPI-U for the labeled year.
+  # NOTE: 42 U.S.C. 9902(2) and the HHS notices update guideline year Y by CPI-U
+  # CY(Y-1)/CY(Y-2). gov/hhs/fpg.yaml uprates guideline year Y with this index by
+  # CY(Y)/CY(Y-1), one year ahead of the statute. Aligning them changes this
+  # shared index, so it is left for a separate PR.
   2022-01-01: 292.6
   2023-01-01: 304.7
   2024-01-01: 313.6
   2025-01-01: 321.9
-  # CBO forecasts.
+  # CBO forecasts. 2026 keeps CBO's January 2025 projection, which the 2026
+  # amounts derived from this index already use (the separate PR on the
+  # statutory lag above would revisit it). Later years grow it at CBO's
+  # February 2026 calendar-year CPI-U growth: 2026 * CBO CPI-U (year) / CBO CPI-U (2026).
   2026-01-01: 328.4
-  2027-01-01: 336.1
-  2028-01-01: 343.6
-  2029-01-01: 351.3
-  2030-01-01: 359.2
-  2031-01-01: 367.2
-  2032-01-01: 375.5
-  2033-01-01: 383.9
-  2034-01-01: 392.5
-  2035-01-01: 401.3
-  # Values for 2036-2100 are set programmatically in uprating_extensions.py
+  2027-01-01: 336.766 # 328.4 * 340.260 / 331.807
+  2028-01-01: 344.719 # 328.4 * 348.295 / 331.807
+  2029-01-01: 352.606 # 328.4 * 356.264 / 331.807
+  2030-01-01: 360.587 # 328.4 * 364.328 / 331.807
+  2031-01-01: 368.732 # 328.4 * 372.557 / 331.807
+  2032-01-01: 377.055 # 328.4 * 380.967 / 331.807
+  2033-01-01: 385.564 # 328.4 * 389.564 / 331.807
+  2034-01-01: 394.265 # 328.4 * 398.355 / 331.807
+  2035-01-01: 403.163 # 328.4 * 407.346 / 331.807
+  2036-01-01: 412.265 # 328.4 * 416.542 / 331.807
+  # Values for 2037-2100 are set programmatically in uprating_extensions.py
 metadata:
   economy: false
   unit: currency-USD
@@ -28,6 +36,17 @@ metadata:
       href: https://www.govinfo.gov/app/details/FR-2025-01-17/2025-01377
     - title: 2024 Annual Update of the HHS Poverty Guidelines
       href: https://www.federalregister.gov/documents/2024/01/17/2024-00796/annual-update-of-the-hhs-poverty-guidelines
-    - title: CBO Budget and Economic Outlook | 2024 to 2034
-      # Jan 2025 Economic Projections | 2. Calendar Year | Row 51
-      href: https://www.cbo.gov/data/budget-economic-data#4
+    - title: 42 U.S. Code § 9902(2)
+      href: https://www.law.cornell.edu/uscode/text/42/9902#2
+    - title: 2026 Annual Update of the HHS Poverty Guidelines
+      href: https://www.federalregister.gov/documents/2026/01/15/2026-00755/annual-update-of-the-hhs-poverty-guidelines
+    - title: CBO | Economic Projections | January 2025
+      # 2026: Sheet 2. Calendar Year, Row 53, CPI-U 328.446 (Row 51 in the original January 2025 release, before CBO's April 30, 2025 update)
+      href: https://www.cbo.gov/system/files/2025-01/51135-2025-01-Economic-Projections.xlsx
+    - title: CBO | Economic Projections | January 2025, calendar-year CSV (variable cpiu)
+      href: https://github.com/US-CBO/cbo-data/blob/284a95665f9f2f74ed1f482feb629b43fce323da/data/economic/economic_projections/calendar_2025-01.csv
+    - title: CBO | Economic Projections | February 2026
+      # Sheet: 2. Calendar Year, Row 53: CPI-U
+      href: https://www.cbo.gov/system/files/2026-02/51135-2026-02-Economic-Projections.xlsx
+    - title: CBO | Economic Projections | February 2026, calendar-year CSV (variable cpiu)
+      href: https://github.com/US-CBO/cbo-data/blob/284a95665f9f2f74ed1f482feb629b43fce323da/data/economic/economic_projections/calendar_2026-02.csv
diff --git a/policyengine_us/parameters/gov/irs/payroll/social_security/cap.yaml b/policyengine_us/parameters/gov/irs/payroll/social_security/cap.yaml
index 28db185a1c4..61deb3ed7d6 100644
--- a/policyengine_us/parameters/gov/irs/payroll/social_security/cap.yaml
+++ b/policyengine_us/parameters/gov/irs/payroll/social_security/cap.yaml
@@ -61,15 +61,22 @@ values:
   # Official SSA determinations.
   2026-01-01: 184_500
   2027-01-01: 192_300
-  # CBO forecast.
-  2028-01-01: 198_600
-  2029-01-01: 206_400
-  2030-01-01: 214_200
-  2031-01-01: 222_300
-  2032-01-01: 230_100
-  2033-01-01: 237_900
-  2034-01-01: 246_000
-  2035-01-01: 254_400
+  # Forecasts apply 42 U.S.C. 430(b) to the projected NAWI in
+  # parameters/gov/ssa/nawi.yaml, which follows CBO's February 2026 CBB
+  # growth from the published 2025 NAWI:
+  # CBB(Y) = 60_600 * NAWI(Y-2) / 22_935.42, rounded to the nearest $300.
+  # The levels sit above CBO's tp_ss_max_earnings (2036: 260_400 against
+  # 258_600), because NAWI grows from SSA's published 2025 value; only CBO's
+  # growth is used.
+  2028-01-01: 199_200 # 60_600 * 75_428.91 / 22_935.42 = 199_298.38
+  2029-01-01: 206_700 # 60_600 * 78_286.07 / 22_935.42 = 206_847.57
+  2030-01-01: 214_200 # 60_600 * 81_028.94 / 22_935.42 = 214_094.78
+  2031-01-01: 221_400 # 60_600 * 83_771.81 / 22_935.42 = 221_342.00
+  2032-01-01: 228_600 # 60_600 * 86_514.68 / 22_935.42 = 228_589.21
+  2033-01-01: 236_400 # 60_600 * 89_486.12 / 22_935.42 = 236_440.36
+  2034-01-01: 243_900 # 60_600 * 92_343.28 / 22_935.42 = 243_989.55
+  2035-01-01: 252_000 # 60_600 * 95_429.00 / 22_935.42 = 252_142.64
+  2036-01-01: 260_400 # 60_600 * 98_514.73 / 22_935.42 = 260_295.76
 metadata:
   unit: currency-USD
   period: year
@@ -87,6 +94,8 @@ metadata:
       href: https://www.ssa.gov/oact/cola/cbb.html
     - title: 2027 Cost-of-Living Adjustment (COLA) Fact Sheet
       href: https://www.ssa.gov/news/en/cola/factsheets/2027.html
-    - title: CBO Tax Parameters and Effective Marginal Tax Rates | Jan 2025
-      # 1. Tax Parameters. Row 161.
-      href: https://www.cbo.gov/system/files/2025-01/53724-2025-01-Tax-Parameters.xlsx
+    - title: CBO | Tax Parameters and Effective Marginal Tax Rates | February 2026
+      # Sheet: 1. Tax Parameters, Row 155: Maximum taxable earnings for the Social Security payroll tax
+      href: https://www.cbo.gov/system/files/2026-02/53724-2026-02-Tax-Parameters.xlsx
+    - title: CBO | Tax Parameters | February 2026, CSV (variable tp_ss_max_earnings)
+      href: https://github.com/US-CBO/cbo-data/blob/284a95665f9f2f74ed1f482feb629b43fce323da/data/budget/tax_parameters/annual_cy_2026-02.csv
diff --git a/policyengine_us/parameters/gov/ssa/nawi.yaml b/policyengine_us/parameters/gov/ssa/nawi.yaml
index dd71e24f276..5012c080da5 100644
--- a/policyengine_us/parameters/gov/ssa/nawi.yaml
+++ b/policyengine_us/parameters/gov/ssa/nawi.yaml
@@ -75,37 +75,25 @@ values:
   2023-01-01: 66_621.80 # NAWI(Y-2) for CBB(2025)
   2024-01-01: 69_846.57 # NAWI(Y-2) for CBB(2026)
   2025-01-01: 72_800.33 # NAWI(Y-2) for CBB(2027); published 2026-10-14
-  # Back out NAWI from CBO's forecast of the payroll tax cap, in
-  # parameters/gov/irs/payroll/social_security/cap.yaml
-  # The formula to derive NAWI(Y-2) from CBB(Y) is:
-  # NAWI(Y-2) approx = CBB(Y) * (NAWI_1992 / CBB_1994)
-  # where NAWI_1992 = 22_935.42 and CBB_1994 = 60_600.
-  # CBB(Y) is the Contribution and Benefit Base (payroll tax cap) for year Y.
-  # NAWI(Y-2) is the National Average Wage Index for year Y-2.
+  # The contribution and benefit base (CBB, the payroll tax cap) for year Y is
+  # CBB(Y) = CBB_1994 * NAWI(Y-2) / NAWI_1992, rounded to the nearest $300,
+  # where NAWI_1992 = 22_935.42 and CBB_1994 = 60_600. So CBB growth tracks
+  # NAWI growth two years earlier.
 
-  # For 2026 NAWI, derived from CBO CBB(2028) = 198_600: 198_600 * (22_935.42 / 60_600)
-  2026-01-01: 75_168.61
-  # For 2027 NAWI, derived from CBO CBB(2029) = 206_400: 206_400 * (22_935.42 / 60_600)
-  2027-01-01: 78_124.71
-  # For 2028 NAWI, derived from CBO CBB(2030) = 214_200: 214_200 * (22_935.42 / 60_600)
-  2028-01-01: 81_080.80
-  # For 2029 NAWI, derived from CBO CBB(2031) = 222_300: 222_300 * (22_935.42 / 60_600)
-  2029-01-01: 84_149.34
-  # For 2030 NAWI, derived from CBO CBB(2032) = 230_100: 230_100 * (22_935.42 / 60_600)
-  2030-01-01: 87_090.55
-  # For 2031 NAWI, derived from CBO CBB(2033) = 237_900: 237_900 * (22_935.42 / 60_600)
-  2031-01-01: 90_031.76
-  # For 2032 NAWI, derived from CBO CBB(2034) = 246_000: 246_000 * (22_935.42 / 60_600)
-  2032-01-01: 93_088.94
-  # For 2033 NAWI, derived from CBO CBB(2035) = 254_400: 254_400 * (22_935.42 / 60_600)
-  2033-01-01: 96_258.56
-  # For 2034 NAWI, projected using the growth rate from NAWI(2032) to NAWI(2033).
-  # Growth Multiplier = NAWI(2033) / NAWI(2032) = 96_258.56 / 93_088.94.
-  # NAWI(2034) = NAWI(2033) * Growth Multiplier.
-  2034-01-01: 99_536.06
-  # For 2035 NAWI, projected using the growth rate from NAWI(2032) to NAWI(2033).
-  # NAWI(2035) = NAWI(2034) * Growth Multiplier.
-  2035-01-01: 102_920.73
+  # Later years carry the published NAWI(2025) forward at the wage growth
+  # implied by CBO's February 2026 CBB projections (tax parameter
+  # tp_ss_max_earnings): NAWI(Y-2) = NAWI(2025) * CBO CBB(Y) / CBO CBB(2027),
+  # where CBO CBB(2027) = 191_100.
+  2026-01-01: 75_428.91 # CBO CBB(2028) = 198_000: 72_800.33 * 198_000 / 191_100
+  2027-01-01: 78_286.07 # CBO CBB(2029) = 205_500
+  2028-01-01: 81_028.94 # CBO CBB(2030) = 212_700
+  2029-01-01: 83_771.81 # CBO CBB(2031) = 219_900
+  2030-01-01: 86_514.68 # CBO CBB(2032) = 227_100
+  2031-01-01: 89_486.12 # CBO CBB(2033) = 234_900
+  2032-01-01: 92_343.28 # CBO CBB(2034) = 242_400
+  2033-01-01: 95_429.00 # CBO CBB(2035) = 250_500
+  2034-01-01: 98_514.73 # CBO CBB(2036) = 258_600
+  # Values for 2035-2100 are set programmatically in uprating_extensions.py
 metadata:
   unit: currency-USD
   period: year
@@ -114,5 +102,8 @@ metadata:
   reference:
     - title: Social Security National Average Wage Index
       href: https://www.ssa.gov/oact/cola/AWI.html#Series
-    - title: 2027 Cost-of-Living Adjustment (COLA) Fact Sheet
-      href: https://www.ssa.gov/news/en/cola/factsheets/2027.html
+    - title: CBO | Tax Parameters and Effective Marginal Tax Rates | February 2026
+      # Sheet: 1. Tax Parameters, Row 155: Maximum taxable earnings for the Social Security payroll tax
+      href: https://www.cbo.gov/system/files/2026-02/53724-2026-02-Tax-Parameters.xlsx
+    - title: CBO | Tax Parameters | February 2026, CSV (variable tp_ss_max_earnings)
+      href: https://github.com/US-CBO/cbo-data/blob/284a95665f9f2f74ed1f482feb629b43fce323da/data/budget/tax_parameters/annual_cy_2026-02.csv
diff --git a/policyengine_us/parameters/gov/ssa/uprating.yaml b/policyengine_us/parameters/gov/ssa/uprating.yaml
index 1f20e9256d6..e348ffe7e79 100644
--- a/policyengine_us/parameters/gov/ssa/uprating.yaml
+++ b/policyengine_us/parameters/gov/ssa/uprating.yaml
@@ -7,26 +7,39 @@ values:
   2025-01-01: 308.729 # 2024Q3: (308.501 + 308.640 + 309.046) / 3
   2026-01-01: 317.265 # 2025Q3: (316.349 + 317.306 + 318.139) / 3
   2027-01-01: 328.746 # 2026Q3: (327.104 + 328.481 + 330.654) / 3
-  # Forecasts from marrying CPI-W actuals with CBO's CPI-U forecast.
-  2028-01-01: 332.241 # 2027Q3: 337.3 * 306.199 / 310.989
-  2029-01-01: 339.431 # 2028Q3: 344.6 * 306.199 / 310.989
-  2030-01-01: 346.917 # 2029Q3: 352.2 * 306.199 / 310.989
-  2031-01-01: 354.6 # 2030Q3: 360.0 * 306.199 / 310.989
-  2032-01-01: 362.579 # 2031Q3: 368.1 * 306.199 / 310.989
-  2033-01-01: 370.656 # 2032Q3: 376.3 * 306.199 / 310.989
-  2034-01-01: 379.028 # 2033Q3: 384.8 * 306.199 / 310.989
-  2035-01-01: 387.598 # 2034Q3: 393.5 * 306.199 / 310.989
-  # Values for 2036-2100 are set programmatically in uprating_extensions.py
+  # Forecasts carry the 2026Q3 CPI-W actual forward at CBO's February 2026
+  # quarterly CPI-U growth: 2026Q3 actual * CBO CPI-U (Q3) / CBO CPI-U (2026Q3).
+  # CBO's Economic Projections publish no CPI-W series, so CBO CPI-U Q3/Q3
+  # growth stands in for CPI-W Q3/Q3. CBO's own projected COLAs (2.3% a year
+  # for 2029-2036) match this growth (2.26% a year) to the tenth of a percent
+  # that CBO publishes.
+  2028-01-01: 336.945 # 2027Q3: 328.746 * 341.281 / 332.976
+  2029-01-01: 344.854 # 2028Q3: 328.746 * 349.291 / 332.976
+  2030-01-01: 352.722 # 2029Q3: 328.746 * 357.260 / 332.976
+  2031-01-01: 360.699 # 2030Q3: 328.746 * 365.340 / 332.976
+  2032-01-01: 368.845 # 2031Q3: 328.746 * 373.591 / 332.976
+  2033-01-01: 377.171 # 2032Q3: 328.746 * 382.024 / 332.976
+  2034-01-01: 385.681 # 2033Q3: 328.746 * 390.644 / 332.976
+  2035-01-01: 394.385 # 2034Q3: 328.746 * 399.460 / 332.976
+  2036-01-01: 403.287 # 2035Q3: 328.746 * 408.476 / 332.976
+  # Values for 2037-2100 are set programmatically in uprating_extensions.py
 metadata:
   economy: false
   unit: currency-USD
   label: SSA uprating
   reference:
-    - title: Historical values
+    - title: SSA | Cost-of-living adjustments, 1975-present
       href: https://www.ssa.gov/oact/cola/colaseries.html
+    - title: 42 U.S. Code § 415(i)
+      href: https://www.law.cornell.edu/uscode/text/42/415#i
     - title: BLS CPI-W, U.S. city average, all items, not seasonally adjusted (CWUR0000SA0)
       href: https://data.bls.gov/timeseries/CWUR0000SA0
     - title: 2027 Cost-of-Living Adjustment (COLA) Fact Sheet
       href: https://www.ssa.gov/news/en/cola/factsheets/2027.html
-    - title: CBO Economic Projections, February 2024.
-      href: https://www.cbo.gov/publication/59710
+    - title: CBO | Economic Projections | February 2026
+      # Sheet: 1. Quarterly, Row 53: CPI-U
+      href: https://www.cbo.gov/system/files/2026-02/51135-2026-02-Economic-Projections.xlsx
+    - title: CBO | Economic Projections | February 2026, quarterly CSV (variable cpiu)
+      href: https://github.com/US-CBO/cbo-data/blob/284a95665f9f2f74ed1f482feb629b43fce323da/data/economic/economic_projections/quarterly_2026-02.csv
+    - title: CBO | The Budget and Economic Outlook, 2026 to 2036 | February 2026, Chapter 3, Social Security (projected COLAs)
+      href: https://www.cbo.gov/system/files/2026-02/61882-Outlook-2026.pdf#page=74
diff --git a/policyengine_us/parameters/gov/usda/snap/uprating.yaml b/policyengine_us/parameters/gov/usda/snap/uprating.yaml
index abe3dbd5815..1f97ac2dcc9 100644
--- a/policyengine_us/parameters/gov/usda/snap/uprating.yaml
+++ b/policyengine_us/parameters/gov/usda/snap/uprating.yaml
@@ -8,24 +8,34 @@ values:
   2024-10-01: 314.175 # 2024-06.
   2025-10-01: 322.561 # 2025-06.
   2026-10-01: 333.952 # 2026-06.
-  # Forecasts from CBO's Q2 forecasts.
-  2027-10-01: 335.5 # 2027Q2
-  2028-10-01: 342.7 # 2028Q2
-  2029-10-01: 350.3 # 2029Q2
-  2030-10-01: 358.1 # 2030Q2
-  2031-10-01: 366.1 # 2031Q2
-  2032-10-01: 374.3 # 2032Q2
-  2033-10-01: 382.7 # 2033Q2
-  2034-10-01: 391.3 # 2034Q2
-  # Values for 2035-2100 are set programmatically in uprating.py
+  # Forecasts carry the June 2026 actual forward at CBO's February 2026
+  # quarterly CPI-U growth: June 2026 actual * CBO CPI-U (Q2) / CBO CPI-U (2026Q2).
+  2027-10-01: 342.578 # 2027Q2: 333.952 * 339.250 / 330.708
+  2028-10-01: 350.71 # 2028Q2: 333.952 * 347.303 / 330.708
+  2029-10-01: 358.747 # 2029Q2: 333.952 * 355.262 / 330.708
+  2030-10-01: 366.868 # 2030Q2: 333.952 * 363.304 / 330.708
+  2031-10-01: 375.156 # 2031Q2: 333.952 * 371.512 / 330.708
+  2032-10-01: 383.625 # 2032Q2: 333.952 * 379.898 / 330.708
+  2033-10-01: 392.282 # 2033Q2: 333.952 * 388.471 / 330.708
+  2034-10-01: 401.134 # 2034Q2: 333.952 * 397.237 / 330.708
+  2035-10-01: 410.188 # 2035Q2: 333.952 * 406.203 / 330.708
+  2036-10-01: 419.448 # 2036Q2: 333.952 * 415.373 / 330.708
+  # Values for 2037-2100 are set programmatically in uprating_extensions.py
 metadata:
   unit: currency-USD
   label: SNAP uprating
   economy: false
   reference:
-    - title: 7 U.S. Code § 2012(u)(4)
-      href: https://www.law.cornell.edu/uscode/text/7/2012#u_4
+    - title: 7 U.S. Code § 2012(u)(3)(C)
+      href: https://www.law.cornell.edu/uscode/text/7/2012#u_3_C
+    - title: 7 U.S. Code § 2012(u)(4) (2023 edition, before Pub. L. 119-21)
+      href: https://www.govinfo.gov/content/pkg/USCODE-2023-title7/html/USCODE-2023-title7-chap51-sec2012.htm
+    - title: 7 CFR 273.10(e)(4)(ii)
+      href: https://www.ecfr.gov/current/title-7/part-273/section-273.10#p-273.10(e)(4)(ii)
     - title: BLS Consumer Price Index for All Urban Consumers (CPI-U), all items, U.S. city average, not seasonally adjusted (CUUR0000SA0)
       href: https://data.bls.gov/timeseries/CUUR0000SA0
-    - title: CBO Economic Projections, February 2024.
-      href: https://www.cbo.gov/publication/59710
+    - title: CBO | Economic Projections | February 2026
+      # Sheet: 1. Quarterly, Row 53: CPI-U
+      href: https://www.cbo.gov/system/files/2026-02/51135-2026-02-Economic-Projections.xlsx
+    - title: CBO | Economic Projections | February 2026, quarterly CSV (variable cpiu)
+      href: https://github.com/US-CBO/cbo-data/blob/284a95665f9f2f74ed1f482feb629b43fce323da/data/economic/economic_projections/quarterly_2026-02.csv
diff --git a/policyengine_us/parameters/uprating_extensions.py b/policyengine_us/parameters/uprating_extensions.py
index c1c598de334..79d70ccfe58 100644
--- a/policyengine_us/parameters/uprating_extensions.py
+++ b/policyengine_us/parameters/uprating_extensions.py
@@ -23,7 +23,11 @@
 
 
 def get_irs_cpi(parameters: ParameterNode, year: int) -> float:
-    """Calculate IRS CPI based on Chained CPI-U average from Sep to Aug."""
+    """Average chained CPI-U from August of ``year - 1`` through July of ``year``.
+
+    26 U.S.C. 1(f) uses the 12 months ending August; #9105 tracks the
+    one-month offset.
+    """
     cpi = parameters.gov.bls.cpi.c_cpi_u
     end = instant(f"{year}-08-01")
     start = end.offset(-MONTHS_IN_YEAR, MONTH)
@@ -779,32 +783,27 @@ def extend_social_security_payroll_cap(
     """
     Extend the Social Security contribution and benefit base through `end_year`.
 
-    This follows the statutory formula in 20 CFR 404.1048 using the projected
-    national average wage index (NAWI), rather than extrapolating the cap
-    independently.
+    Follows 42 U.S.C. 430(b) on the projected national average wage index
+    (NAWI): the base for year Y is the larger of the base in effect for Y - 1
+    and the 1994 base ($60,600) times NAWI(Y - 2) / NAWI(1992), rounded to the
+    nearest $300 (a multiple of $150 rounds up). 20 CFR 404.1048(b)(2)(i)
+    still states the pre-1995 chained formula, which Pub. L. 103-296,
+    sec. 321(g)(1), replaced for bases after 1994.
     """
     cap = parameters.gov.irs.payroll.social_security.cap
     nawi = parameters.gov.ssa.nawi
-
-    last_increase_determination_year = last_projected_year - 1
-    if cap(f"{last_projected_year}-01-01") <= cap(f"{last_projected_year - 1}-01-01"):
-        for year in range(last_projected_year - 1, 1992, -1):
-            if cap(f"{year}-01-01") > cap(f"{year - 1}-01-01"):
-                last_increase_determination_year = year - 1
-                break
+    base_1994 = cap("1994-01-01")
+    nawi_1992 = nawi("1992-01-01")
 
     for year in range(last_projected_year + 1, end_year + 1):
-        determination_year = year - 1
-        current_cap = cap(f"{determination_year}-01-01")
-        numerator = nawi(f"{determination_year - 1}-01-01")
-        denominator = nawi(f"{last_increase_determination_year - 1}-01-01")
+        current_cap = cap(f"{year - 1}-01-01")
         proposed_cap = round_social_security_payroll_cap(
-            current_cap * numerator / denominator
+            base_1994 * nawi(f"{year - 2}-01-01") / nawi_1992
+        )
+        cap.update(
+            period=f"year:{year}-01-01:1",
+            value=max(current_cap, proposed_cap),
         )
-        new_cap = max(current_cap, proposed_cap)
-        cap.update(period=f"year:{year}-01-01:1", value=new_cap)
-        if new_cap > current_cap:
-            last_increase_determination_year = determination_year
 
     final_value = cap(f"{end_year}-01-01")
     cap.update(start=instant(f"{end_year}-01-01"), value=final_value)
@@ -936,7 +935,9 @@ def set_all_uprating_parameters(parameters: ParameterNode) -> ParameterNode:
 
     # IRS uprating - special case that computes from CPI
     IRS_UPRATING_START_YEAR = 2010
-    IRS_LAST_PROJECTED_YEAR = 2035
+    # 2036 averages chained CPI-U from August 2034 to July 2035 (see #9105);
+    # the 2035 instant holds CBO's February 2026 calendar-2035 point.
+    IRS_LAST_PROJECTED_YEAR = 2036
 
     uprating_index = parameters.gov.irs.uprating
 
@@ -956,31 +957,31 @@ def set_all_uprating_parameters(parameters: ParameterNode) -> ParameterNode:
         uprating_index.update(period=f"year:{year}-01-01:1", value=irs_cpi)
     uprating_index.update(start=instant(f"{END_YEAR}-01-01"), value=irs_cpi)
 
-    # SNAP uprating (October values, last projection year 2034)
+    # SNAP uprating (October values, last projection year 2036)
     extend_parameter_values(
         parameters.gov.usda.snap.uprating,
-        last_projected_year=2034,
+        last_projected_year=2036,
         end_year=END_YEAR,
         period_month=10,
         period_day=1,
     )
 
-    # SSA uprating (January values, last projection year 2035)
+    # SSA uprating (January values, last projection year 2036)
     extend_parameter_values(
         parameters.gov.ssa.uprating,
-        last_projected_year=2035,
+        last_projected_year=2036,
         end_year=END_YEAR,
         period_month=1,
         period_day=1,
     )
 
     # Social Security National Average Wage Index (January values, last
-    # projection year 2035). The payroll tax contribution and benefit base is
-    # indexed to NAWI, so this must remain available through the full long-run
-    # projection horizon.
+    # projection year 2034, the NAWI behind CBO's 2036 CBB). The payroll tax
+    # contribution and benefit base is indexed to NAWI, so this must remain
+    # available through the full long-run projection horizon.
     extend_parameter_values(
         parameters.gov.ssa.nawi,
-        last_projected_year=2035,
+        last_projected_year=2034,
         end_year=END_YEAR,
         period_month=1,
         period_day=1,
@@ -991,7 +992,7 @@ def set_all_uprating_parameters(parameters: ParameterNode) -> ParameterNode:
     # independently.
     extend_social_security_payroll_cap(
         parameters,
-        last_projected_year=2035,
+        last_projected_year=2036,
         end_year=END_YEAR,
     )
 
@@ -1000,37 +1001,41 @@ def set_all_uprating_parameters(parameters: ParameterNode) -> ParameterNode:
         end_year=END_YEAR,
     )
 
-    # HHS poverty guideline uprating (January values, last projection year 2035)
+    # HHS poverty guideline uprating (January values, last projection year 2036)
     extend_parameter_values(
         parameters.gov.hhs.uprating,
-        last_projected_year=2035,
+        last_projected_year=2036,
         end_year=END_YEAR,
         period_month=1,
         period_day=1,
     )
 
-    # CPI-U (February values, last projection year 2034)
+    # CPI-U (February values, last projection year 2036). Each February
+    # instant holds CBO's February 2026 calendar-year average for that year
+    # (the "# YYYY value" comments name the tax year it feeds), so CBO's last
+    # point, calendar 2036, sits at the 2036 instant.
     extend_parameter_values(
         parameters.gov.bls.cpi.cpi_u,
-        last_projected_year=2034,
+        last_projected_year=2036,
         end_year=END_YEAR,
         period_month=2,
         period_day=1,
     )
 
-    # Chained CPI-U (February values, last projection year 2034)
+    # Chained CPI-U (February values, last projection year 2036), as for CPI-U.
     extend_parameter_values(
         parameters.gov.bls.cpi.c_cpi_u,
-        last_projected_year=2034,
+        last_projected_year=2036,
         end_year=END_YEAR,
         period_month=2,
         period_day=1,
     )
 
-    # CPI-W (February values, last projection year 2034)
+    # CPI-W (February values, last projection year 2036; quarterly
+    # projections run through 2036Q4)
     extend_parameter_values(
         parameters.gov.bls.cpi.cpi_w,
-        last_projected_year=2034,
+        last_projected_year=2036,
         end_year=END_YEAR,
         period_month=2,
         period_day=1,
diff --git a/policyengine_us/tests/microsimulation/data/test_extend_single_year_dataset.py b/policyengine_us/tests/microsimulation/data/test_extend_single_year_dataset.py
index b9f367f41f4..8ed4f90782a 100644
--- a/policyengine_us/tests/microsimulation/data/test_extend_single_year_dataset.py
+++ b/policyengine_us/tests/microsimulation/data/test_extend_single_year_dataset.py
@@ -1191,14 +1191,15 @@ class FakeParam:
 
     def test_with_real_cpi_u_parameter(self):
         """Verify get_parameter_last_year works on the actual CPI-U
-        parameter YAML, returning 2035 (not 2100 from uprating_extensions)."""
+        parameter YAML, returning 2036 (not 2100 from uprating_extensions)."""
         from policyengine_us.system import system
 
         cpi_u = _resolve_parameter(system.parameters, "gov.bls.cpi.cpi_u")
         last_year = get_parameter_last_year(cpi_u)
-        # CPI-U YAML currently extends to 2035; if the YAML is updated,
-        # this assertion should be updated to match.
-        assert last_year == 2035
+        # CPI-U YAML currently extends to 2036 (CBO's February 2026
+        # projections); if the YAML is updated, this assertion should be
+        # updated to match.
+        assert last_year == 2036
 
 
 # ---------------------------------------------------------------------------
diff --git a/policyengine_us/tests/policy/baseline/gov/irs/deductions/standard/basic_standard_deduction.yaml b/policyengine_us/tests/policy/baseline/gov/irs/deductions/standard/basic_standard_deduction.yaml
index 55633ed743d..b399f60da0e 100644
--- a/policyengine_us/tests/policy/baseline/gov/irs/deductions/standard/basic_standard_deduction.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/irs/deductions/standard/basic_standard_deduction.yaml
@@ -165,11 +165,11 @@
   # Past CBO's 2036 horizon, 63(c)(4)(B)(i) increases the 63(c)(5)(A) $500
   # by the 1(f)(3) adjustment with calendar year 1987 as the base year.
   # C-CPI-U for the 12 months ending August 2041: uprating_extensions.py
-  # extends c_cpi_u.yaml past 2034 at its 2033-2034 growth rate,
-  # 214.9 x (214.9 / 210.8)^7 = 245.922.
+  # extends c_cpi_u.yaml past 2036 at its 2035-2036 growth rate,
+  # 223.5 x (223.5 / 219.2)^5 = 246.299.
   # 1(f)(3)(A)(ii) and (B): CPI-U Sep 1986-Aug 1987 average 111.983 x
   # 135.993 / 238.649 = 63.813.
-  # Increase = $500 x (245.922 / 63.813 - 1) = $1,426.89, rounded down to
+  # Increase = $500 x (246.299 / 63.813 - 1) = $1,429.85, rounded down to
   # $1,400, so $1,900.
   period: 2042
   input:
@@ -188,8 +188,8 @@
     basic_standard_deduction: 1_900
 
 - name: 2042 dependent filer with $3,000 of wages gets $650 plus earned income
-  # Same 2041 C-CPI-U of 245.922 and 1997 denominator of 90.886.
-  # Increase = $250 x (245.922 / 90.886 - 1) = $426.46, rounded down to
+  # Same 2041 C-CPI-U of 246.299 and 1997 denominator of 90.886.
+  # Increase = $250 x (246.299 / 90.886 - 1) = $427.49, rounded down to
   # $400, so $650. max($1,900, $650 + $3,000) = $3,650.
   period: 2042
   input:
diff --git a/policyengine_us/tests/policy/baseline/gov/states/or/delc/erdc/integration.yaml b/policyengine_us/tests/policy/baseline/gov/states/or/delc/erdc/integration.yaml
index 6618d6ff153..e1828cc44a4 100644
--- a/policyengine_us/tests/policy/baseline/gov/states/or/delc/erdc/integration.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/states/or/delc/erdc/integration.yaml
@@ -35,6 +35,9 @@
     or_erdc_eligible: true
     or_erdc: 1_490
 
+# 2027 2-person FPG = (15,960 + 5,680) x 336.766 / 328.4 = 22,191.28.
+# Initial limit = ceil(22,191.28 / 12 x 2) = ceil(3,698.55) = 3,699. The rule
+# is income < limit, so income of 3,699 is ineligible.
 - name: Case 2, initial applicant at the strict income limit is ineligible.
   period: 2027-01
   absolute_error_margin: 0.1
@@ -52,13 +55,13 @@
     spm_units:
       spm_unit:
         members: [parent, child]
-        or_erdc_countable_income: 3_692
+        or_erdc_countable_income: 3_699
     households:
       household:
         members: [parent, child]
         state_code: OR
   output:
-    or_erdc_countable_income: 3_692
+    or_erdc_countable_income: 3_699
     or_erdc_income_eligible: false
     or_erdc_eligible: false
     or_erdc: 0
diff --git a/policyengine_us/tests/policy/baseline/gov/usda/snap/snap_max_allotment.yaml b/policyengine_us/tests/policy/baseline/gov/usda/snap/snap_max_allotment.yaml
index acf9ef722a7..b4ab5de4ba5 100644
--- a/policyengine_us/tests/policy/baseline/gov/usda/snap/snap_max_allotment.yaml
+++ b/policyengine_us/tests/policy/baseline/gov/usda/snap/snap_max_allotment.yaml
@@ -32,5 +32,5 @@
       2027: CONTIGUOUS_US
     snap_unit_size: 4
   output:
-    # 1023 * 335.5 / 333.952
-    snap_max_allotment: 1027.74
+    # 1023 * 342.578 / 333.952
+    snap_max_allotment: 1049.42
diff --git a/policyengine_us/tests/policy/baseline/parameters/test_uprating_extensions.py b/policyengine_us/tests/policy/baseline/parameters/test_uprating_extensions.py
index 6ff5f115dee..01e350f6715 100644
--- a/policyengine_us/tests/policy/baseline/parameters/test_uprating_extensions.py
+++ b/policyengine_us/tests/policy/baseline/parameters/test_uprating_extensions.py
@@ -291,7 +291,7 @@ def test_float_dollar_inputs_have_long_run_upraters():
 
 
 def test_ssa_nawi_and_payroll_cap_extend_to_2100():
-    """Test that the SSA NAWI and payroll cap do not flatten after 2035."""
+    """Test that the SSA NAWI and payroll cap do not flatten after 2036."""
     parameters = PARAMETERS
 
     nawi = parameters.gov.ssa.nawi
@@ -309,10 +309,15 @@ def test_ssa_nawi_and_payroll_cap_extend_to_2100():
             f"Payroll cap should increase from {test_years[i - 1]} to {test_years[i]}"
         )
 
-    for year in [2036, 2040, 2050, 2100]:
-        current_cap = payroll_cap(f"{year - 1}-01-01")
-        expected_cap = round_social_security_payroll_cap(
-            current_cap * nawi(f"{year - 2}-01-01") / nawi(f"{year - 3}-01-01")
+    # 42 U.S.C. 430(b): fixed 1994 base, never below the prior year's base.
+    for year in [2037, 2040, 2050, 2073, 2100]:
+        expected_cap = max(
+            payroll_cap(f"{year - 1}-01-01"),
+            round_social_security_payroll_cap(
+                payroll_cap("1994-01-01")
+                * nawi(f"{year - 2}-01-01")
+                / nawi("1992-01-01")
+            ),
         )
         assert payroll_cap(f"{year}-01-01") == expected_cap
 
@@ -325,7 +330,7 @@ def test_social_security_payroll_cap_formula_matches_known_values():
     nawi = parameters.gov.ssa.nawi
 
     expected_2025_cap = round_social_security_payroll_cap(
-        payroll_cap("2024-01-01") * nawi("2023-01-01") / nawi("2022-01-01")
+        payroll_cap("1994-01-01") * nawi("2023-01-01") / nawi("1992-01-01")
     )
 
     assert expected_2025_cap == payroll_cap("2025-01-01")
@@ -412,13 +417,234 @@ def test_social_security_parameters_include_latest_official_2027_values():
     assert pia.thresholds[2] == 8_077
 
 
+# CBO February 2026 projections, from US-CBO/cbo-data at 284a956, whose CSVs
+# equal the workbook rows: quarterly_2026-02.csv and calendar_2026-02.csv
+# (cpiu and chained_cpiu; Economic Projections sheets "1. Quarterly", row 53,
+# and "2. Calendar Year", rows 53 and 57) and annual_cy_2026-02.csv
+# (tp_ss_max_earnings; Tax Parameters sheet "1. Tax Parameters", row 155).
+CBO_2026_02_QUARTERLY_CPI_U = {
+    "2026Q2": 330.708,
+    "2026Q3": 332.976,
+    "2026Q4": 335.132,
+    "2027Q1": 337.213,
+    "2027Q2": 339.250,
+    "2027Q3": 341.281,
+    "2027Q4": 343.298,
+    "2028Q1": 345.305,
+    "2028Q2": 347.303,
+    "2028Q3": 349.291,
+    "2028Q4": 351.280,
+    "2029Q1": 353.269,
+    "2029Q2": 355.262,
+    "2029Q3": 357.260,
+    "2029Q4": 359.265,
+    "2030Q1": 361.279,
+    "2030Q2": 363.304,
+    "2030Q3": 365.340,
+    "2030Q4": 367.386,
+    "2031Q1": 369.444,
+    "2031Q2": 371.512,
+    "2031Q3": 373.591,
+    "2031Q4": 375.682,
+    "2032Q1": 377.784,
+    "2032Q2": 379.898,
+    "2032Q3": 382.024,
+    "2032Q4": 384.161,
+    "2033Q1": 386.310,
+    "2033Q2": 388.471,
+    "2033Q3": 390.644,
+    "2033Q4": 392.830,
+    "2034Q1": 395.027,
+    "2034Q2": 397.237,
+    "2034Q3": 399.460,
+    "2034Q4": 401.695,
+    "2035Q1": 403.943,
+    "2035Q2": 406.203,
+    "2035Q3": 408.476,
+    "2035Q4": 410.762,
+    "2036Q1": 413.061,
+    "2036Q2": 415.373,
+    "2036Q3": 417.698,
+    "2036Q4": 420.036,
+}
+CBO_2026_02_CALENDAR_CPI_U = {
+    2026: 331.807,
+    2027: 340.260,
+    2028: 348.295,
+    2029: 356.264,
+    2030: 364.328,
+    2031: 372.557,
+    2032: 380.967,
+    2033: 389.564,
+    2034: 398.355,
+    2035: 407.346,
+    2036: 416.542,
+}
+CBO_2026_02_CALENDAR_C_CPI_U = {
+    2027: 187.212,
+    2028: 191.088,
+    2029: 194.917,
+    2030: 198.775,
+    2031: 202.695,
+    2032: 206.688,
+    2033: 210.759,
+    2034: 214.912,
+    2035: 219.152,
+    2036: 223.479,
+}
+CBO_2026_02_CBB = {
+    2027: 191_100,
+    2028: 198_000,
+    2029: 205_500,
+    2030: 212_700,
+    2031: 219_900,
+    2032: 227_100,
+    2033: 234_900,
+    2034: 242_400,
+    2035: 250_500,
+    2036: 258_600,
+}
+
+# The latest actuals that each projection grows from.
+SSA_2026Q3_CPI_W = 328.746  # BLS CWUR0000SA0, July-September 2026 mean
+JUNE_2026_CPI_W = 327.075  # BLS CWUR0000SA0
+JUNE_2026_CPI_U = 333.952  # BLS CUUR0000SA0
+NAWI_2025 = 72_800.33  # SSA AWI series
+HHS_2026 = 328.4  # CBO January 2025 calendar-2026 CPI-U (328.446)
+
+
+def _cbo_2026_02_projection_cases():
+    quarterly = CBO_2026_02_QUARTERLY_CPI_U
+    calendar = CBO_2026_02_CALENDAR_CPI_U
+    cases = []
+    # SSA: 2026Q3 CPI-W x CBO CPI-U Q3(Y - 1) / 2026Q3.
+    for year in range(2028, 2037):
+        growth = quarterly[f"{year - 1}Q3"] / quarterly["2026Q3"]
+        cases.append(
+            ("gov.ssa.uprating", f"{year}-01-01", SSA_2026Q3_CPI_W * growth, 3)
+        )
+    # SNAP: June 2026 CPI-U x CBO CPI-U Q2(Y) / 2026Q2.
+    for year in range(2027, 2037):
+        growth = quarterly[f"{year}Q2"] / quarterly["2026Q2"]
+        cases.append(
+            ("gov.usda.snap.uprating", f"{year}-10-01", JUNE_2026_CPI_U * growth, 3)
+        )
+    # HHS: 2026 value x CBO calendar CPI-U(Y) / calendar 2026.
+    for year in range(2027, 2037):
+        growth = calendar[year] / calendar[2026]
+        cases.append(("gov.hhs.uprating", f"{year}-01-01", HHS_2026 * growth, 3))
+    # CPI-W: each CBO CPI-U quarter at the June 2026 CPI-W / CPI-U ratio, at
+    # the quarter's middle month.
+    for quarter, cpi_u in quarterly.items():
+        if quarter < "2026Q3":
+            continue
+        year, month = int(quarter[:4]), 3 * int(quarter[-1]) - 1
+        cases.append(
+            (
+                "gov.bls.cpi.cpi_w",
+                f"{year}-{month:02d}-01",
+                cpi_u * JUNE_2026_CPI_W / JUNE_2026_CPI_U,
+                3,
+            )
+        )
+    # NAWI: SSA's 2025 AWI x CBO CBB(Y + 2) / CBB 2027.
+    for year in range(2026, 2035):
+        growth = CBO_2026_02_CBB[year + 2] / CBO_2026_02_CBB[2027]
+        cases.append(("gov.ssa.nawi", f"{year}-01-01", NAWI_2025 * growth, 2))
+    # CPI-U and chained CPI-U: CBO's calendar-year Y average at the Y-02-01
+    # instant, to one decimal.
+    for year in range(2027, 2037):
+        cases.append(("gov.bls.cpi.cpi_u", f"{year}-02-01", calendar[year], 1))
+        cases.append(
+            (
+                "gov.bls.cpi.c_cpi_u",
+                f"{year}-02-01",
+                CBO_2026_02_CALENDAR_C_CPI_U[year],
+                1,
+            )
+        )
+    return cases
+
+
+CBO_2026_02_PROJECTION_CASES = _cbo_2026_02_projection_cases()
+
+
+@pytest.mark.parametrize(
+    "path,date,expected,decimals",
+    CBO_2026_02_PROJECTION_CASES,
+    ids=[f"{path}@{date}" for path, date, _, _ in CBO_2026_02_PROJECTION_CASES],
+)
+def test_upraters_encode_cbo_february_2026_projections(path, date, expected, decimals):
+    """Each projected value applies CBO's February 2026 growth to its anchor.
+
+    extend_parameter_values grows every year after a series' last CBO point at
+    the ratio of its last two points, so these values, the last two included,
+    also set the 2037-2100 path.
+    """
+    assert PARAMETERS.get_child(path)(date) == round(expected, decimals)
+
+
+def test_projected_payroll_caps_follow_430b_through_2036():
+    """2028-2036 caps apply 42 U.S.C. 430(b) to the CBO-based NAWI."""
+    cap = PARAMETERS.gov.irs.payroll.social_security.cap
+    nawi = PARAMETERS.gov.ssa.nawi
+    for year in range(2028, 2037):
+        assert cap(f"{year}-01-01") == round_social_security_payroll_cap(
+            cap("1994-01-01") * nawi(f"{year - 2}-01-01") / nawi("1992-01-01")
+        )
+    assert cap("2036-01-01") == 260_400
+
+
+def test_irs_uprating_averages_cbo_chained_cpi_u_points():
+    """IRS(Y) averages chained CPI-U from August Y - 2 to July Y - 1 (#9105).
+
+    Six months read the February Y - 2 point and six read February Y - 1.
+    """
+    irs = PARAMETERS.gov.irs.uprating
+    c_cpi_u = {
+        year: round(value, 1) for year, value in CBO_2026_02_CALENDAR_C_CPI_U.items()
+    }
+    for year in range(2029, 2037):
+        assert irs(f"{year}-01-01") == pytest.approx(
+            (6 * c_cpi_u[year - 2] + 6 * c_cpi_u[year - 1]) / 12, rel=1e-12
+        )
+
+
+@pytest.mark.parametrize(
+    "path,last_projected_year,date_suffix",
+    [
+        ("gov.irs.uprating", 2036, "-01-01"),
+        ("gov.ssa.uprating", 2036, "-01-01"),
+        ("gov.usda.snap.uprating", 2036, "-10-01"),
+        ("gov.hhs.uprating", 2036, "-01-01"),
+        ("gov.ssa.nawi", 2034, "-01-01"),
+        ("gov.bls.cpi.cpi_u", 2036, "-02-01"),
+        ("gov.bls.cpi.c_cpi_u", 2036, "-02-01"),
+        ("gov.bls.cpi.cpi_w", 2036, "-02-01"),
+    ],
+)
+def test_upraters_extrapolate_only_after_cbo_projections(
+    path, last_projected_year, date_suffix
+):
+    """Each series holds its final projected growth after CBO's last year."""
+    parameter = PARAMETERS.get_child(path)
+    last_growth = parameter(f"{last_projected_year}{date_suffix}") / parameter(
+        f"{last_projected_year - 1}{date_suffix}"
+    )
+    for year in [last_projected_year + 1, last_projected_year + 2, 2050, 2100]:
+        growth = parameter(f"{year}{date_suffix}") / parameter(
+            f"{year - 1}{date_suffix}"
+        )
+        assert growth == pytest.approx(last_growth, rel=1e-12)
+
+
 def test_social_security_wage_indexed_parameters_follow_statutory_rounding():
     """Wage-indexed benefit parameters should use lagged NAWI and statutory rounding."""
     parameters = PARAMETERS
     nawi = parameters.gov.ssa.nawi
     social_security = parameters.gov.ssa.social_security
 
-    for year in [2027, 2036, 2050, 2100]:
+    for year in [2027, 2036, 2037, 2050, 2100]:
         date = f"{year}-01-01"
         prior_date = f"{year - 1}-01-01"
         determination_nawi = nawi(f"{year - 2}-01-01")
diff --git a/policyengine_us/tests/policy/contrib/states/ca/ab2591/ca_ab2591.yaml b/policyengine_us/tests/policy/contrib/states/ca/ab2591/ca_ab2591.yaml
index 760f94e4e75..856516fc3fc 100644
--- a/policyengine_us/tests/policy/contrib/states/ca/ab2591/ca_ab2591.yaml
+++ b/policyengine_us/tests/policy/contrib/states/ca/ab2591/ca_ab2591.yaml
@@ -2,12 +2,12 @@
 # Allows taxpayers to elect a standard deduction equal to the federal
 # poverty line for their household size.
 # Effective for taxable years beginning on or after July 1, 2027.
-# 2027 federal poverty guidelines (CONTIGUOUS_US):
-#   first person = $16,334
-#   additional person = $5,813
-#   1-person FPL  = $16,334
-#   2-person FPL  = $22,147
-#   4-person FPL  = $33,774
+# 2027 federal poverty guidelines (CONTIGUOUS_US), 2026 values x 336.766 / 328.4:
+#   first person = $16,366.58
+#   additional person = $5,824.70
+#   1-person FPL  = $16,367 (rounded)
+#   2-person FPL  = $22,191 (rounded)
+#   4-person FPL  = $33,841 (rounded)
 
 - name: Single filer uses one-person FPL.
   period: 2027
@@ -28,7 +28,7 @@
         members: [person1]
         state_code: CA
   output:
-    ca_standard_deduction: 16_334
+    ca_standard_deduction: 16_367
 
 - name: Head of household with one child uses two-person FPL.
   period: 2027
@@ -53,7 +53,7 @@
         members: [person1, person2]
         state_code: CA
   output:
-    ca_standard_deduction: 22_147
+    ca_standard_deduction: 22_191
 
 - name: Head of household with two children still uses two-person FPL.
   # Bill R&TC 17073.5(b)(2) fixes HoH at the two-person FPL regardless of size.
@@ -82,7 +82,7 @@
         members: [person1, person2, person3]
         state_code: CA
   output:
-    ca_standard_deduction: 22_147
+    ca_standard_deduction: 22_191
 
 - name: Joint filers with no children use two-person FPL.
   period: 2027
@@ -107,7 +107,7 @@
         members: [person1, person2]
         state_code: CA
   output:
-    ca_standard_deduction: 22_147
+    ca_standard_deduction: 22_191
 
 - name: Joint filers with two children use four-person FPL.
   # Bill R&TC 17073.5(b)(3) scales joint FPL with the number of persons in the household.
@@ -139,7 +139,7 @@
         members: [person1, person2, person3, person4]
         state_code: CA
   output:
-    ca_standard_deduction: 33_774
+    ca_standard_deduction: 33_841
 
 - name: Married filing separately uses one-person FPL.
   period: 2027
@@ -161,7 +161,7 @@
         members: [person1]
         state_code: CA
   output:
-    ca_standard_deduction: 16_334
+    ca_standard_deduction: 16_367
 
 - name: Reform inactive leaves baseline CA standard deduction unchanged.
   period: 2027