diff --git a/changelog.d/ssa-2027-cola.changed.md b/changelog.d/ssa-2027-cola.changed.md
new file mode 100644
index 00000000000..9aa688781a9
--- /dev/null
+++ b/changelog.d/ssa-2027-cola.changed.md
@@ -0,0 +1 @@
+Update Social Security and SSI parameters for the 2027 cost-of-living adjustment: the 2027 SSA CPI-W uprating index, SSI federal payment amounts, the SSI student earned income exclusion, the contribution and benefit base, and the 2025 national average wage index that sets the 2027 wage-indexed amounts.
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 a5e30e50148..28db185a1c4 100644
--- a/policyengine_us/parameters/gov/irs/payroll/social_security/cap.yaml
+++ b/policyengine_us/parameters/gov/irs/payroll/social_security/cap.yaml
@@ -58,10 +58,10 @@ values:
   2023-01-01: 160_200
   2024-01-01: 168_600
   2025-01-01: 176_100
-  # Official SSA determination.
+  # Official SSA determinations.
   2026-01-01: 184_500
+  2027-01-01: 192_300
   # CBO forecast.
-  2027-01-01: 192_600
   2028-01-01: 198_600
   2029-01-01: 206_400
   2030-01-01: 214_200
@@ -85,6 +85,8 @@ metadata:
       # Defines wages for FICA tax purposes as amounts from the benefit base.
     - title: Contribution And Benefit Base
       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
diff --git a/policyengine_us/parameters/gov/ssa/nawi.yaml b/policyengine_us/parameters/gov/ssa/nawi.yaml
index 1cdec755b94..dd71e24f276 100644
--- a/policyengine_us/parameters/gov/ssa/nawi.yaml
+++ b/policyengine_us/parameters/gov/ssa/nawi.yaml
@@ -74,6 +74,7 @@ values:
   2022-01-01: 63_795.13 # NAWI(Y-2) for CBB(2024)
   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:
@@ -82,8 +83,6 @@ values:
   # 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.
 
-  # For 2025 NAWI, derived from CBO CBB(2027) = 192_600: 192_600 * (22_935.42 / 60_600)
-  2025-01-01: 72_891.30
   # 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)
@@ -115,3 +114,5 @@ 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
diff --git a/policyengine_us/parameters/gov/ssa/ssi/amount/couple.yaml b/policyengine_us/parameters/gov/ssa/ssi/amount/couple.yaml
index f92766064d1..91e34285c67 100644
--- a/policyengine_us/parameters/gov/ssa/ssi/amount/couple.yaml
+++ b/policyengine_us/parameters/gov/ssa/ssi/amount/couple.yaml
@@ -53,6 +53,7 @@ values:
   2024-01-01: 1_415
   2025-01-01: 1_450
   2026-01-01: 1_491
+  2027-01-01: 1_544
 metadata:
   label: Monthly maximum Federal SSI payment amounts for an eligible individual with an eligible spouse
   uprating: gov.ssa.uprating
@@ -61,3 +62,5 @@ metadata:
   reference:
     - title: SSI Federal Payment Amounts
       href: https://www.ssa.gov/oact/cola/SSIamts.html
+    - title: 2027 Cost-of-Living Adjustment (COLA) Fact Sheet
+      href: https://www.ssa.gov/news/en/cola/factsheets/2027.html
diff --git a/policyengine_us/parameters/gov/ssa/ssi/amount/individual.yaml b/policyengine_us/parameters/gov/ssa/ssi/amount/individual.yaml
index d7388c56e36..9cd8809ac58 100644
--- a/policyengine_us/parameters/gov/ssa/ssi/amount/individual.yaml
+++ b/policyengine_us/parameters/gov/ssa/ssi/amount/individual.yaml
@@ -53,6 +53,7 @@ values:
   2024-01-01: 943
   2025-01-01: 967
   2026-01-01: 994
+  2027-01-01: 1_029
 metadata:
   label: Monthly maximum Federal SSI payment amounts for an eligible individual
   uprating: gov.ssa.uprating
@@ -61,3 +62,5 @@ metadata:
   reference:
     - title: SSI Federal Payment Amounts
       href: https://www.ssa.gov/oact/cola/SSIamts.html
+    - title: 2027 Cost-of-Living Adjustment (COLA) Fact Sheet
+      href: https://www.ssa.gov/news/en/cola/factsheets/2027.html
diff --git a/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/amount.yaml b/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/amount.yaml
index 7a07b701727..ce92585ac24 100644
--- a/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/amount.yaml
+++ b/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/amount.yaml
@@ -25,6 +25,7 @@ values:
   2024-01-01: 2_290
   2025-01-01: 2_350
   2026-01-01: 2_410
+  2027-01-01: 2_500
 metadata:
   uprating:
     parameter: gov.ssa.uprating
@@ -67,3 +68,5 @@ metadata:
       href: https://www.ssa.gov/OACT/ssir/SSI24/V_E_WorkIncentives.html
     - title: Student Earned Income Exclusion for SSI
       href: https://www.ssa.gov/oact/cola/studentEIE.html
+    - title: 2027 Cost-of-Living Adjustment (COLA) Fact Sheet
+      href: https://www.ssa.gov/news/en/cola/factsheets/2027.html
diff --git a/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/cap.yaml b/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/cap.yaml
index 1254da0a6e3..daac488481e 100644
--- a/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/cap.yaml
+++ b/policyengine_us/parameters/gov/ssa/ssi/income/exclusions/blind_or_disabled_working_student/cap.yaml
@@ -25,6 +25,7 @@ values:
   2024-01-01: 9_230
   2025-01-01: 9_460
   2026-01-01: 9_730
+  2027-01-01: 10_080
 metadata:
   uprating:
     parameter: gov.ssa.uprating
@@ -67,3 +68,5 @@ metadata:
       href: https://www.ssa.gov/OACT/ssir/SSI24/V_E_WorkIncentives.html
     - title: Student Earned Income Exclusion for SSI
       href: https://www.ssa.gov/oact/cola/studentEIE.html
+    - title: 2027 Cost-of-Living Adjustment (COLA) Fact Sheet
+      href: https://www.ssa.gov/news/en/cola/factsheets/2027.html
diff --git a/policyengine_us/parameters/gov/ssa/uprating.yaml b/policyengine_us/parameters/gov/ssa/uprating.yaml
index c8940519456..1f20e9256d6 100644
--- a/policyengine_us/parameters/gov/ssa/uprating.yaml
+++ b/policyengine_us/parameters/gov/ssa/uprating.yaml
@@ -6,8 +6,8 @@ values:
   2024-01-01: 301.236 # 2023Q3: (299.899 + 301.551 + 302.257) / 3
   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.
-  2027-01-01: 326.149 # 2026Q3: 330.1 * 306.199 / 310.989
   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
@@ -24,5 +24,9 @@ metadata:
   reference:
     - title: Historical values
       href: https://www.ssa.gov/oact/cola/colaseries.html
+    - 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
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 1f26e51c99b..6ff5f115dee 100644
--- a/policyengine_us/tests/policy/baseline/parameters/test_uprating_extensions.py
+++ b/policyengine_us/tests/policy/baseline/parameters/test_uprating_extensions.py
@@ -337,6 +337,13 @@ def test_social_security_payroll_cap_formula_matches_known_values():
     assert expected_2026_cap == 184_500
     assert expected_2026_cap == payroll_cap("2026-01-01")
 
+    expected_2027_cap = round_social_security_payroll_cap(
+        payroll_cap("1994-01-01") * nawi("2025-01-01") / nawi("1992-01-01")
+    )
+
+    assert expected_2027_cap == 192_300
+    assert expected_2027_cap == payroll_cap("2027-01-01")
+
 
 def test_social_security_parameters_include_latest_official_2026_values():
     """Test announced 2026 SSA values before forecasts resume."""
@@ -369,6 +376,42 @@ def test_social_security_parameters_include_latest_official_2026_values():
     assert pia.thresholds[2] == 7_749
 
 
+def test_social_security_parameters_include_latest_official_2027_values():
+    """Test announced 2027 SSA values, including those the extension derives from NAWI."""
+    parameters = PARAMETERS
+    ssa = parameters.gov.ssa
+    social_security = ssa.social_security
+
+    # 3.6% COLA: 2026Q3 CPI-W average over the 2025Q3 average.
+    assert ssa.uprating("2027-01-01") == 328.746
+    assert round(ssa.uprating("2027-01-01") / ssa.uprating("2026-01-01") - 1, 3) == (
+        0.036
+    )
+    assert ssa.ssi.amount.individual("2027-01-01") == 1_029
+    assert ssa.ssi.amount.couple("2027-01-01") == 1_544
+    student = ssa.ssi.income.exclusions.blind_or_disabled_working_student
+    assert student.amount("2027-01-01") == 2_500
+    assert student.cap("2027-01-01") == 10_080
+
+    assert parameters.gov.irs.payroll.social_security.cap("2027-01-01") == 192_300
+    assert social_security.wage_base("2027-01-01") == 192_300
+    assert social_security.quarters_of_coverage_threshold("2027-01-01") == 1_970
+    assert social_security.earnings_test.exempt_amount_under_fra("2027-01-01") == (
+        25_560
+    )
+    assert social_security.earnings_test.exempt_amount_year_of_fra("2027-01-01") == (
+        67_920
+    )
+    assert ssa.sga.non_blind("2027-01-01") == 1_770
+    assert ssa.sga.blind("2027-01-01") == 2_950
+
+    # SSA's published 2025 AWI sets the 2027 PIA bend points.
+    assert ssa.nawi("2025-01-01") == 72_800.33
+    pia = social_security.pia.formula_factors("2027-01-01")
+    assert pia.thresholds[1] == 1_340
+    assert pia.thresholds[2] == 8_077
+
+
 def test_social_security_wage_indexed_parameters_follow_statutory_rounding():
     """Wage-indexed benefit parameters should use lagged NAWI and statutory rounding."""
     parameters = PARAMETERS