PolicyEngine · MaxGhenis · Aug 20, 2026
diff --git a/changelog.d/uk-extra-291.changed.md b/changelog.d/uk-extra-291.changed.md
@@ -0,0 +1 @@
+The uk extra floors move to policyengine-uk>=2.91 across the build, data, and frame shards, so the next UK release records a built-with model that carries the retention-elasticity semantics and CGT response hardening the policyengine.py certification gate pairs against.
diff --git a/packages/microcosm-build/pyproject.toml b/packages/microcosm-build/pyproject.toml
@@ -36,7 +36,7 @@ us = [
 # The UK extra adds the rules engine for local metric generation from a
 # Microcosm UK H5. Target tables remain explicit inputs, and the base package
 # still does not import policyengine-uk at import time.
-uk = ["policyengine-uk>=2.88", "h5py>=3", "tables>=3"]
+uk = ["policyengine-uk>=2.91", "h5py>=3", "tables>=3"]
 
 [project.scripts]
 microcosm-export-us-l0-refit-h5 = "microcosm.build.us_runtime.l0_refit_export:main"

diff --git a/packages/microcosm-build/src/microcosm/build/uk/cgt_source_stages.json b/packages/microcosm-build/src/microcosm/build/uk/cgt_source_stages.json
@@ -43,7 +43,7 @@
         {
           "role": "policy_parameters",
           "kind": "versioned_parameter_tree",
-          "dependency": "policyengine-uk>=2.88 via microcosm-build[uk]",
+          "dependency": "policyengine-uk>=2.91 via microcosm-build[uk]",
           "parameters": [
             "gov.hmrc.income_tax.allowances.personal_allowance.amount",
             "gov.hmrc.income_tax.allowances.personal_allowance.maximum_ANI",

diff --git a/packages/microcosm-build/src/microcosm/build/uk/release_input_coverage_manifest.json b/packages/microcosm-build/src/microcosm/build/uk/release_input_coverage_manifest.json
@@ -471,7 +471,7 @@
    ],
    "required_mass_change_reason": "Amounts-only capital gains redraw: household weights pass through unchanged and total household mass is conserved.",
    "source_manifest": "cgt_source_stages.json",
-   "source_manifest_sha256": "16b68f1d222116278421b210d3d9de0d06edcdf25d68f5a29dbf0f52ca63384a",
+   "source_manifest_sha256": "ee3a83e738a3b584740603971851f24b28c28c525c4f6abcc7411d9bc6579480",
    "source_vintages": {
     "hmrc_surface": "2023-24",
     "mapped_build_period": "2023"

diff --git a/packages/microcosm-data/pyproject.toml b/packages/microcosm-data/pyproject.toml
@@ -28,7 +28,7 @@ us = ["policyengine-us>=1.745.0,<2"]
 # The UK artifact lives in a PRIVATE repo (UK Data Service licence): loads
 # require an authenticated HF token with access. The loader surfaces the
 # 401 with that explanation rather than retrying.
-uk = ["policyengine-uk>=2.88"]
+uk = ["policyengine-uk>=2.91"]
 
 [project.urls]
 Homepage = "https://microcosm.institute"

diff --git a/packages/microcosm-frame/pyproject.toml b/packages/microcosm-frame/pyproject.toml
@@ -12,7 +12,7 @@ dependencies = [
 [project.optional-dependencies]
 us = ["microunit>=0.1.0"]
 policyengine = ["policyengine-us>=1.745.0,<2", "microunit>=0.1.0"]
-uk = ["policyengine-uk>=2.88"]
+uk = ["policyengine-uk>=2.91"]
 # The Axiom adapter's PyPI-resolvable dependencies. The engine itself
 # (axiom-rules-engine + its dense native extension) is not on PyPI yet and
 # installs from a checkout; see microcosm/frame/adapters/axiom.py.

diff --git a/uv.lock b/uv.lock
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		The uk extra floors move to policyengine-uk>=2.91 across the build, data, and frame shards, so the next UK release records a built-with model that carries the retention-elasticity semantics and CGT response hardening the policyengine.py certification gate pairs against.