Submit a Medicaid/CHIP eligibility inquiry via the CMS FHIR Patient Access API and parse coverage resources

Steps

1. Confirm your plan type falls under the CMS-0057-F rule (Medicaid managed care, CHIP managed care, or Medicaid FFS using modular MMIS) — Patient Access API compliance was required as of January 1, 2026.
2. Obtain OAuth 2.0 credentials from the state or managed care entity's developer portal; the API uses SMART on FHIR scopes such as patient/Coverage.read and patient/ExplanationOfBenefit.read.
3. POST to the token endpoint to obtain a bearer token, then query the Coverage endpoint: GET /fhir/r4/Coverage?patient={patientId} and check the status field for active/inactive.
4. Parse the Coverage resource for period.start, period.end, payor reference, and class entries that encode plan and group identifiers.
5. For prior authorization status, query the ClaimResponse or Task resources as exposed by the payer's FHIR server per CMS-0057-F requirements.
6. Handle 401 (token expired), 403 (missing scope), and 429 (rate limit) errors; refresh tokens use the standard OAuth refresh_token grant.