Add Massachusetts premium assistance (ConnectorCare)

[DTrim99]

Add Massachusetts ConnectorCare premium assistance (PY2026)

Closes #9223

Summary

Adds the Massachusetts ConnectorCare premium wrap — the Health Connector's state subsidy layered on top of the federal ACA premium tax credit under M.G.L. c. 176Q and 956 CMR 12.00. The state pays the gap between the benchmark plan premium, the federal APTC, and a flat per-person monthly enrollee contribution the Board sets annually by plan type (956 CMR 12.12(9)). This PR implements the plan year 2026 flat-dollar schedule ($0/$53/$103/$152/$235 per person per month across five FPL bands).

New node: gov/states/ma/hic/connector_care/ (HIC = Commonwealth Health Insurance Connector Authority). New variables: ma_connector_care, ma_connector_care_eligible, ma_connector_care_member_eligible. The benefit is added to healthcare_benefit_value and registered in programs.yaml with verified_start_year: 2026.

Regulatory Authority

• M.G.L. c. 176Q — Commonwealth Health Insurance Connector Authority enabling statute: https://malegislature.gov/Laws/GeneralLaws/PartI/TitleXXII/Chapter176Q
• 956 CMR 12.00 (amended) — Eligibility, Enrollment, and Hearing Process for Connector Programs:
  • §12.04(1)-(2) non-group and APTC-only eligibility (45 CFR 155.305(f)): amended-956CMR12.00.pdf#page=5
  • §12.04(3)(a)-(c) ConnectorCare eligibility, plan-type income bands, minimum-premium guarantee with full-APTC election: amended-956CMR12.00.pdf#page=6
  • §12.12(9) Board-set annual minimum monthly premium schedule: amended-956CMR12.00.pdf#page=13
• ConnectorCare Overview 2026 (operational program design and exact PY2026 amounts):
  • Eligibility, Table 1 (400% FPL dollar amounts), Table 2 (plan-type FPL bands): ConnectorCare-Overview-2026.pdf#page=1
  • Table 3 (monthly lowest-cost plan premiums per person): ConnectorCare-Overview-2026.pdf#page=2
• 2026 Seal of Approval Board Memo — pilot extended one year in the FY2026 budget; rate filings assumed enhanced APTCs expire end-2025: Board-Memo-2026-Seal-of-Approval-Submission-Summary-070925.pdf#page=6
• 2026 Affordability Schedule Board Memo — enrollee contributions decoupled from the percent-of-income affordability schedule since 2025: Board-Memo-Proposed-2026-Affordability-Schedule-and-MCC-Deductible-Limits-020725.pdf#page=2

Local copies of all four PDFs live under sources/ (the mahealthconnector.org CDN returns 403 on generic user agents).

Eligibility

Three modeled gates, matching the in_effect & income_band & aptc_eligible structure of the other state premium-assistance implementations:

1. Massachusetts residency via defined_for = StateCode.MA (956 CMR 12.04(1)(c)).
2. Income band: 100-400% FPL, both bounds inclusive, via aca_magi_fraction against fpl_floor (1.0) and fpl_limit (4.0). For 2026 the operational program runs Plan Types 2A-3C only: Plan Type 1 (<100% FPL) is eliminated and the 3D tier (400.1-500%) lapsed with the enhanced APTCs, with only 3C (300.1-400%) surviving from the pilot.
   • Reg-vs-Overview conflict, documented in code: the amended regulation text still says "at or below 500 percent of the FPL" and still defines Plan Types 1 and 3D (§12.04(3), #page=6). The consumer-facing 2026 Overview (100-400% only) is treated as controlling for the operational program; the conflict is noted in the parameter and variable documentation so a future re-expansion is a parameter change, not a re-architecture.
3. At least one APTC-eligible member: ma_connector_care_member_eligible = is_aca_ptc_eligible (956 CMR 12.04(3)(a)2 → 45 CFR 155.305(f)). Citizenship/lawful presence, incarceration, no-affordable-employer-coverage, and Medicare/MassHealth exclusions are inherited through the federal PTC eligibility chain rather than re-modeled.

An in_effect parameter gates the program to 2026 onward (pre-2026 program history unmodeled — see Not Modeled).

Benefit Calculation

The PY2026 enrollee contribution is a flat per-person monthly dollar amount by FPL band — decoupled from the percent-of-income affordability schedule since 2025 (Affordability Memo p.2), so this is a single_amount step bracket over aca_magi_fraction with no interpolation:

Plan Type	FPL band	Monthly premium per person
2A	100-150%	$0
2B	150.1-200%	$53
3A	200.1-250%	$103
3B	250.1-300%	$152
3C	300.1-400%	$235

Bracket thresholds use the x.0001 lower-exclusive convention (1.0 → 0, 1.5001 → 53, 2.0001 → 103, 2.5001 → 152, 3.0001 → 235) matching the published "150.1%" banding. A bracket comment notes the 3C tier is a pilot extended through FY2026 that may lapse.

The subsidy:

ma_connector_care = max(0, annual SLCSP − aca_ptc − 12 × per_person_premium × n_eligible_members)

gated by ma_connector_care_eligible, where n_eligible_members counts APTC-eligible members (the CO/WA convention). Documented approximations:

• Benchmark proxy: the actual guarantee is a lowest-cost ConnectorCare-designated plan per region at the Board minimum premium (§12.04(3)(c)); the model uses the existing slcsp (second-lowest-cost silver) as the benchmark, slightly overstating the wrap where the lowest-cost plan is cheaper.
• Full-APTC election: §12.04(3)(c) conditions the minimum premium on electing the full APTC, so the full aca_ptc is netted out.
• Full-year enrollment via MONTHS_IN_YEAR; floored at zero (no clawback where APTC plus contribution exceeds the benchmark, e.g. the $235 3C tier).
• The wrap is a benefit paid to carriers, not taxable income: added to healthcare_benefit_value, not routed through income.

Requirements Coverage

28 requirements were extracted from the sources and approved at the scope checkpoint; all 46 tests pass.

Category	REQs	Status
Eligibility (ELIG-1..6)	6	All covered — residency, in_effect, floor/limit, member gate, federal-chain inheritance
Schedule (SCHED-1..5)	5	All covered — Table 3 amounts, band boundaries, flat-dollar step function, per-person basis, §12.12(9) authority
Calculation (CALC-1..7)	7	All covered — residual formula, full-APTC netting, member count, SLCSP proxy documented, zero floor, annualization, benefit aggregation
Parameters (PARAM-1..5)	5	All covered — in_effect, fpl_limit, fpl_floor, enrollee_premium bracket with #page-anchored references, house style
Variables (VAR-1..4)	4	All covered — three variables with verified reference anchors
Tests (TEST-1..6)	6	Covered; TEST-1 partial — ma_connector_care_member_eligible has no dedicated unit file and is asserted as an output within integration scenarios
Registry (REG-1..3)	3	Covered — programs.yaml entry, changelog fragment, formatting clean. REG-1 deviation: registered as a standalone State entry rather than a state_implementations item under the ACA PTC parent

Test files (run individually with policyengine-core test):

File	Tests
ma_connector_care_eligible.yaml	8
ma_connector_care.yaml (all 12 band boundaries 0.99-4.01, hand-computed $928 residual, zero-floor, edge cases)	23
integration.yaml (incl. a scenario deriving slcsp/aca_ptc/is_aca_ptc_eligible from raw employment income)	8
household/healthcare_benefit_value.yaml (MA wrap case)	7
Total	46

Not Modeled

• Cost-sharing wrap: ConnectorCare's reduced co-pays and out-of-pocket maximums (Overview Table 4) — a separate benefit, excluded as the MD implementation excluded its cost-sharing split.
• Plan choice: enrollees choosing costlier carriers pay premium differentials; the model assumes the lowest-cost plan at the Board minimum, proxied by SLCSP.
• Stale regulation text: the un-repealed 500% ceiling and Plan Types 1 (<100%) and 3D (400.1-500%) in 956 CMR 12.04(3); the 2026 operational bands (2A-3C) are implemented, with both readings documented.
• Pre-2026 program history (2006-2025): affordability-coupled contributions and Plan Types 1/3D — left to future backdating work; in_effect is false before 2026.
• Enrollment mechanics: hardship premium waivers (§12.12(7)), termination/reinstatement, special enrollment periods, monthly carrier payment flows (§12.12(10)).
• Partial-year enrollment and mid-year plan-type changes (§12.12(8)); full-year assumed.
• American Indian / Alaska Native cost-sharing variants (cost-sharing only, out of scope with the wrap).
• Takeup: eligibility implies receipt, matching the MD/WA premium-assistance implementations.

Files Added

changelog.d/
└── ma-premium-assistance.added.md
policyengine_us/
├── programs.yaml                                          (entry added)
├── parameters/gov/states/ma/hic/connector_care/
│   ├── enrollee_premium.yaml
│   ├── fpl_floor.yaml
│   ├── fpl_limit.yaml
│   └── in_effect.yaml
├── variables/gov/states/ma/hic/connector_care/
│   ├── ma_connector_care.py
│   ├── ma_connector_care_eligible.py
│   └── ma_connector_care_member_eligible.py
├── variables/household/income/household/
│   └── healthcare_benefit_value.py                        (adds ma_connector_care)
└── tests/policy/baseline/
    ├── gov/states/ma/hic/connector_care/
    │   ├── integration.yaml
    │   ├── ma_connector_care.yaml
    │   └── ma_connector_care_eligible.yaml
    └── household/healthcare_benefit_value.yaml            (MA case added)

14 files changed, 1,290 insertions.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (63bcfc5) to head (41046b5).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

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[DTrim99]

Review fixes applied (/review-program → /fix-pr)

Full multi-agent review (regulatory, references, code patterns, test coverage, PDF value audit against the ConnectorCare Overview 2026 + amended 956 CMR + board memos). PDF audit 12/0 — all five per-person premiums ($0/$53/$103/$152/$235), the plan-type band boundaries, fpl_floor/fpl_limit, and the residual formula verified; the omitted Type 1 / 3D / 500% bands confirmed intentional (the amended CMR still lists them, but the 2026 Overview operationally supersedes them). Applied the one critical, all should-address items, and suggestions:

Critical

• in_effect.yaml: the Seal-of-Approval Board Memo reference URL 404'd — replaced it with the working board_meetings/2025/07-10-25/ path (verified HTTP 200; #page=6 kept).

Registry / references / docs

• programs.yaml: status: complete → partial (this PR models the premium axis only; cost-sharing / dental / NEMT are out of scope), agency → State and full_name trimmed to match sibling entries (ma_eaedc, co_omnisalud), with a notes line recording the premium-only scope.
• Added a direct ConnectorCare Overview 2026 #page=1 citation on fpl_limit/fpl_floor so the 100–400% band is visible alongside the CMR sub-band cites.
• fpl_floor 1.0→1, fpl_limit 4.0→4, enrollee_premium first bracket 1.0→1 (numerically identical).
• ma_connector_care_member_eligible.py docstring: removed two clauses that overclaimed the federal PTC gate (non-incarceration / affordable employer coverage — is_aca_ptc_eligible doesn't check those).

Tests (50/50 passing)

• A new dedicated ma_connector_care_member_eligible.yaml (3 person-level cases) covering the pass-through gate.
• A multi-member derived-from-raw-income integration scenario (married couple → 189% FPL) with aca_magi_fraction, slcsp, and aca_ptc all derived, asserting a genuine $1,155.92 subsidy.

No parameter values (beyond 1.0→1 / 4.0→4 formatting) or formula logic changed. Rebased onto current main; CI green.

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