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) — with API compliance generally due January 1, 2027.
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