CARIN Blue Button Implementation Guide
The CARIN Consumer Directed Payer Data Exchange (CARIN Blue Button) implementation guide defines how health insurance payers expose claims, coverage, and clinical data to their members via FHIR APIs. It extends CMS's Blue Button 2.0 initiative (originally Medicare-only) to all payer types.
Background
- CMS Blue Button 2.0 — CMS launched this initiative for Medicare beneficiaries to access their claims data via FHIR API at bluebutton.cms.gov
- CARIN Alliance — Extended the concept to commercial payers, creating an industry-wide IG
- CMS Patient Access API — CMS mandated that all impacted payers implement CARIN-aligned FHIR APIs
Key Profiles
C4BB ExplanationOfBenefit (EOB)
The central resource, with variants for different claim types:
| Profile | Claim Type |
|---|---|
| C4BB EOB Inpatient Institutional | Hospital inpatient claims |
| C4BB EOB Outpatient Institutional | Hospital outpatient/facility claims |
| C4BB EOB Professional NonClinician | Physician and professional claims |
| C4BB EOB Pharmacy | Prescription drug claims |
| C4BB EOB Oral | Dental claims |
Each EOB profile includes:
- Adjudication details (allowed, paid, patient responsibility)
- Diagnosis and procedure codes
- Provider information (NPI, name)
- Dates of service
- Benefit period
C4BB Coverage
Member's insurance coverage details — plan identifier, subscriber information, coverage period, network type.
C4BB Patient
The member's demographics — extends US Core Patient.
How Members Access Data
- Member navigates to a third-party health app or payer portal
- App redirects to the payer's OAuth 2.0 authorization server
- Member authenticates and grants consent for data sharing
- App receives an access token
- App queries the payer's FHIR API for the member's EOBs, Coverage, and Patient data
- Data is displayed in the app for the member to review, download, or share
Third-Party App Ecosystem
CARIN Blue Button enables a growing ecosystem of member-facing health apps:
- Personal health record apps
- Cost transparency tools
- Insurance comparison platforms
- Care navigation services
- Financial planning tools
Payers must implement SMART on FHIR app registration and maintain a developer portal for third-party app onboarding.
