X12 278
ASC X12N 278 Health Care Services Review
X12 278 is the EDI transaction US payers use for prior-authorization and referral requests and responses.
X12 278 is the ASC X12N Health Care Services Review transaction, the EDI standard payers and providers use to request and respond to prior authorizations and referrals. It is part of the same X12 EDI family as eligibility (270/271), claim status (276/277), enrollment (834), and claims and remittance (837/835).
The 278 is entrenched in payer operations: it is how authorization requests and decisions move through existing clearinghouse and adjudication plumbing. That is why CMS-0057-F's FHIR-based Prior Authorization API must interoperate with X12 278 rather than replace it overnight.
The practical need, then, is a reliable bridge: FHIR (Da Vinci PAS) on the outward-facing API, X12 278 on the internal side, with faithful round-tripping between them.
How this relates to Health1st
Health1st maps X12 278 ↔ FHIR (Da Vinci PAS) so payers can expose the CMS-0057-F Prior Authorization API on the front end while their existing 278-based systems keep adjudicating authorizations on the back end.
Related terms
PARDD is the CMS-0057-F Prior Authorization API that lets providers query coverage requirements, gather documentation, and submit and track authorization decisions via FHIR.
A FHIR-based API that automates the prior-authorization workflow (checking requirements, gathering documentation, and exchanging decisions) as required by CMS-0057-F.
Da Vinci is the HL7 accelerator that publishes FHIR implementation guides for payer-provider workflows, including prior authorization, coverage, and data exchange.
CMS-0057-F requires impacted US payers to stand up four FHIR APIs: Patient Access, Provider Access, Payer-to-Payer, and Prior Authorization (PARDD). API compliance is generally due January 1, 2027.
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