Access CMS Blue Button 2.0 API to retrieve Medicare claims data for a beneficiary

Steps

1. Register your application at bluebutton.cms.gov developer portal and obtain a client_id and client_secret for the sandbox environment.
2. Implement the OAuth 2.0 authorization code flow: redirect the Medicare beneficiary to the CMS authorization endpoint; after consent, exchange the code for tokens at the token endpoint.
3. Query the FHIR R4 endpoints with the access token; the Blue Button 2.0 API exposes ExplanationOfBenefit (EOB), Patient, and Coverage resources.
4. Retrieve all EOBs for the beneficiary: GET [base]/ExplanationOfBenefit?patient=[id]&_count=50; paginate through results using Bundle next links; EOBs represent Medicare Part A, B, and D claims.
5. Parse EOB.item[].productOrService for procedure codes (CPT/HCPCS), EOB.diagnosis[] for ICD-10 codes, EOB.item[].adjudication[] for payment amounts and adjustment reasons.
6. Access Coverage resources via GET [base]/Coverage?patient=[id] to determine Part A, B, and D enrollment status and effective periods.