FHIR Versions — R4, R4B, R5, R6 · Wiki

R4 (2019) is the version US Core 6+, Blue Button 2.0, DaVinci IGs, and most production EHR endpoints target. Default to R4 unless your stakeholder specifically asks for R5.

R4B (2022) is a maintenance update — wire-compatible with R4 for most apps. Backports the SubscriptionTopic resource.

R5 (2023) introduces structural changes — different MedicationRequest model, restructured Reference handling, new resources. Adoption is patchy as of 2026.

R6 (in ballot 2026) is being driven by US ONC, CMS, and the FHIR-at-Scale Taskforce (FAST). Watch for early implementations in late 2026.

Implementation tip: design your code with a thin FHIR-version adapter layer (e.g., getPatientName(patient: Patient): string) so you can swap versions without rewriting your app.

R4 (2019) is the version US Core 6+, Blue Button 2.0, DaVinci IGs, and most production EHR endpoints target. Default to R4 unless your stakeholder specifically asks for R5.

R4B (2022) is a maintenance update — wire-compatible with R4 for most apps. Backports the SubscriptionTopic resource.

R5 (2023) introduces structural changes — different MedicationRequest model, restructured Reference handling, new resources. Adoption is patchy as of 2026.

R6 (in ballot 2026) is being driven by US ONC, CMS, and the FHIR-at-Scale Taskforce (FAST). Watch for early implementations in late 2026.

Implementation tip: design your code with a thin FHIR-version adapter layer (e.g., getPatientName(patient: Patient): string) so you can swap versions without rewriting your app.