Calibrate ACA take-up contract

changelog.d/added/8168.md

@@ -0,0 +1 @@
+Marketplace take-up can now use reported Marketplace coverage while preserving a simulated take-up switch, with selected Marketplace plan benchmark ratios documented as explicit inputs.

policyengine_us/tests/policy/baseline/gov/aca/ptc/marketplace_net_premium.yaml

@@ -41,3 +41,31 @@
     selected_marketplace_plan_premium_proxy: 8_000
     used_aca_ptc: 0
     marketplace_net_premium: 8_000
+
+- name: Reported unsubsidized Marketplace buyer pays selected plan premium when simulated take-up is disabled.
+  absolute_error_margin: 0.01
+  period: 2026
+  input:
+    people:
+      person1:
+        age: 40
+        has_marketplace_health_coverage_at_interview: true
+        is_medicaid_eligible: false
+        is_chip_eligible: false
+        is_basic_health_program_eligible: false
+        is_aca_eshi_eligible: false
+        is_medicare_eligible: false
+    tax_units:
+      tax_unit:
+        members: [person1]
+        aca_magi_fraction: 5
+        slcsp: 10_000
+        selected_marketplace_plan_benchmark_ratio: 0.8
+        simulated_aca_take_up_if_eligible: false
+  output:
+    pays_aca_premium: [true]
+    takes_up_aca_if_eligible: true
+    is_aca_ptc_eligible: [false]
+    selected_marketplace_plan_premium_proxy: 8_000
+    used_aca_ptc: 0
+    marketplace_net_premium: 8_000

policyengine_us/tests/policy/baseline/gov/aca/takes_up_aca_if_eligible.yaml

@@ -0,0 +1,46 @@
+- name: Case 1, default simulated Marketplace take-up preserves existing ACA take-up behavior.
+  period: 2026
+  output:
+    simulated_aca_take_up_if_eligible: true
+    takes_up_aca_if_eligible: true
+
+- name: Case 2, reported Marketplace coverage triggers take-up when simulated take-up is disabled.
+  period: 2026
+  input:
+    people:
+      person1:
+        has_marketplace_health_coverage_at_interview: true
+    tax_units:
+      tax_unit:
+        members: [person1]
+        simulated_aca_take_up_if_eligible: false
+  output:
+    takes_up_aca_if_eligible: true
+
+- name: Case 3, no reported Marketplace coverage means no take-up when simulated take-up is disabled.
+  period: 2026
+  input:
+    people:
+      person1:
+        has_marketplace_health_coverage_at_interview: false
+    tax_units:
+      tax_unit:
+        members: [person1]
+        simulated_aca_take_up_if_eligible: false
+  output:
+    takes_up_aca_if_eligible: false
+
+- name: Case 4, reported Marketplace coverage for one member triggers tax-unit take-up.
+  period: 2026
+  input:
+    people:
+      person1:
+        has_marketplace_health_coverage_at_interview: false
+      person2:
+        has_marketplace_health_coverage_at_interview: true
+    tax_units:
+      tax_unit:
+        members: [person1, person2]
+        simulated_aca_take_up_if_eligible: false
+  output:
+    takes_up_aca_if_eligible: true

policyengine_us/variables/gov/aca/ptc/selected_marketplace_plan_benchmark_ratio.py

@@ -8,3 +8,9 @@ class selected_marketplace_plan_benchmark_ratio(Variable):
     unit = "/1"
     definition_period = YEAR
     default_value = 1.0
+    documentation = (
+        "Ratio of the selected Marketplace plan gross premium to the second "
+        "lowest cost silver plan benchmark premium. This is an explicit "
+        "user- or data-supplied input; when absent, the model assumes the "
+        "selected plan premium equals the benchmark premium."
+    )

policyengine_us/variables/gov/aca/simulated_aca_take_up_if_eligible.py

@@ -0,0 +1,14 @@
+from policyengine_us.model_api import *
+
+
+class simulated_aca_take_up_if_eligible(Variable):
+    value_type = bool
+    entity = TaxUnit
+    label = "Whether a tax unit is simulated to take up ACA if eligible"
+    definition_period = YEAR
+    default_value = True
+    documentation = (
+        "Reform-responsive Marketplace take-up switch for tax units without "
+        "reported Marketplace coverage at interview. Reported Marketplace "
+        "coverage is handled in takes_up_aca_if_eligible."
+    )

policyengine_us/variables/gov/aca/takes_up_aca_if_eligible.py

@@ -7,3 +7,17 @@ class takes_up_aca_if_eligible(Variable):
     label = "Whether an eligible tax unit takes up ACA"
     definition_period = YEAR
     default_value = True
+    documentation = (
+        "Whether the tax unit takes up Marketplace coverage when otherwise "
+        "eligible. Reported Marketplace coverage at interview is treated as "
+        "observed take-up; otherwise take-up follows the simulated take-up "
+        "switch."
+    )
+
+    def formula(tax_unit, period, parameters):
+        person = tax_unit.members
+        reported_marketplace_coverage = tax_unit.any(
+            person("has_marketplace_health_coverage_at_interview", period)
+        )
+        simulated_take_up = tax_unit("simulated_aca_take_up_if_eligible", period)
+        return reported_marketplace_coverage | simulated_take_up