Methodology

The NSAidr decoder is a deterministic 8-axis decision tree implementing the federal No Surprises Act patient-protection rules under 45 CFR Part 149. Every verdict is reproducible by hand from the statute pins.

The 8 axes

1. Service type — emergency, OON ancillary at INN facility, air ambulance, ground ambulance, scheduled OON with notice-and-consent, or other-non-NSA.
2. Payer type — commercial fully-insured, self-funded ERISA, Medicare, Medicare Advantage, Medicaid, TRICARE, VA, or uninsured/self-pay.
3. State of service — 50 states + DC. Drives state ground-ambulance overlay and state IDR overlay.
4. Facility status — in-network, out-of-network, or unknown.
5. Provider status — in-network, out-of-network, or unknown.
6. Notice-and-consent waiver — yes, no, or unsure. Applies only to scheduled OON non-emergency services at INN facilities; cannot waive ancillary services.
7. Bill date + EOB receipt date — drives the 30-business-day open-negotiation clock and 4-business-day IDR initiation window.
8. GFE amount + actual bill amount — self-pay only. Drives PPDR eligibility ($400 GFE-vs-actual delta threshold).

Branching rules

• Medicare / Medicaid / TRICARE / VA → NSA does not apply (separate beneficiary protection rules).
• Uninsured / self-pay → PPDR branch. Eligibility requires GFE-vs-actual delta ≥ $400.
• Ground ambulance → NSA does not cover. State law controls; the state ground-ambulance matrix is the entry point.
• Emergency, air ambulance, OON ancillary at INN facility → NSA applies. Patient files NSA complaint via CMS Help Desk; provider/plan run Federal IDR.
• Scheduled OON with signed notice-and-consent waiver → NSA waiver applies (limited; not ancillary services).
• ERISA self-funded plan → DOL/EBSA enforcement, not state DOI. State IDR pathways apply only to fully-insured state-regulated plans.

Statute anchors

• Public Law 116-260 (CAA 2021), Title I of Division BB — primary source ↗
• PHSA §2799A-1 (42 U.S.C. §300gg-111) — primary source ↗
• PHSA §2799A-2 (42 U.S.C. §300gg-112) — primary source ↗
• PHSA §2799A-5 (42 U.S.C. §300gg-115) — primary source ↗
• PHSA §2799B-1 (42 U.S.C. §300gg-131) — primary source ↗
• PHSA §2799B-7 (42 U.S.C. §300gg-137) — primary source ↗
• 45 CFR Part 149 — primary source ↗
• 45 CFR §149.510 — primary source ↗
• 45 CFR §149.620 — primary source ↗
• CMS — No Surprises Act landing — primary source ↗
• CMS — IDR / payment disputes (providers and plans) — primary source ↗
• CMS — PPDR for uninsured / self-pay patients — primary source ↗
• Federal IDR portal — nsa-idr.cms.gov — primary source ↗
• CMS No Surprises Help Desk — 1-800-985-3059 — primary source ↗
• HHS ASPE — No Surprises Act evaluation reports — primary source ↗
• CRS Report R48738 — NSA IDR Process Data Analysis — primary source ↗

Validation — 5 anonymous synthetic NSA scenarios

The decoder is unit-tested against 5 anonymous synthetic scenarios reproduced TO THE LETTER of the dispute-path verdict. The fixtures live at src/lib/fixtures.ts and tests at src/lib/__tests__/decoder.test.ts. The build fails if any fixture reproduces incorrectly.

1. Air-ambulance OON bill, self-funded ERISA plan (Texas) — expected verdict: federal_idr
2. Emergency-room OON bill, commercial fully-insured plan (California) — expected verdict: federal_idr
3. Self-pay surgery, actual bill exceeds GFE by $1,200 (Florida) — expected verdict: ppdr
4. Ground-ambulance bill, commercial plan in Colorado (state law applies) — expected verdict: state_ground_amb
5. Medicare patient with a balance bill — NSA does not apply — expected verdict: nsa_does_not_apply

Refresh discipline

State ground-ambulance balance-billing laws are revised annually. We run a quarterly review against each state DOI / state legislature primary URL. Federal rulemaking (HHS / CMS / DOL) is monitored on a continuous basis; any change to 45 CFR Part 149 triggers a citation-manifest update.