Short answer: USCDI (United States Core Data for Interoperability) is the standardised list of data classes and data elements that certified health IT in the US must be able to capture and exchange: demographics, problems, medications, allergies, lab results, vital signs, immunizations, procedures, clinical notes, encounters, care team members, provenance and more. It is published by the federal health IT office (ASTP/ONC) and updated yearly; the version a certified system must support is set by rule. FHIR US Core is the implementation guide that says how each USCDI element is represented in FHIR, so USCDI is the what and US Core the how. USCDI also defined the initial scope of information blocking, before that scope widened to all electronic health information.
What is in it
USCDI version 3, the baseline required of certified health IT from 1 January 2026 under the HTI-1 rule, contains about 20 data classes and 90 elements: patient demographics, allergies, problems, medications, laboratory results, vital signs, immunizations, procedures, clinical notes, encounters, health status assessments, goals and care team, provenance and implantable device identifiers, each mapped to a FHIR US Core profile.
The classes:
| Data class | Examples of elements | US Core profile |
|---|---|---|
| Patient Demographics / Information | Name, date of birth, sex, race, ethnicity, preferred language, address, identifiers, gender identity, sexual orientation | Patient |
| Allergies and Intolerances | Substance, reaction | AllergyIntolerance |
| Problems | Problems, SDOH problems, date of diagnosis, date of resolution | Condition (Problems and Health Concerns) |
| Medications | Medications, dose, route, frequency | MedicationRequest |
| Laboratory | Tests, values and results, result status, specimen type, reference range | Observation Lab, DiagnosticReport Lab |
| Vital Signs | Blood pressure, heart rate, temperature, weight, height, BMI, SpO2, pediatric percentiles | Vital Signs Observations |
| Immunizations | Vaccine, lot, date | Immunization |
| Procedures | Procedures, performance time, reason, SDOH interventions | Procedure |
| Clinical Notes | Consultation, discharge summary, history and physical, imaging narrative, laboratory report narrative, pathology report narrative, procedure note, progress note | DocumentReference, DiagnosticReport |
| Encounter Information | Type, diagnosis, time, location, disposition | Encounter |
| Health Status / Assessments | Smoking status, functional status, disability status, mental and cognitive status, pregnancy status, SDOH assessment | Observation profiles |
| Goals, Care Plan, Care Team Members | Patient goals, SDOH goals, care team member name and role | Goal, CarePlan, CareTeam |
| Diagnostic Imaging | Tests, reports | DiagnosticReport Note |
| Health Insurance Information | Coverage status, type, member identifier, payer | Coverage |
| Provenance | Author, author time stamp, author organization | Provenance |
| Unique Device Identifier(s) | UDI for implantable devices | Implantable Device |
| Facility Information, Medical Devices, Orders, Observations (v4+) | Facility name and type, device identifiers, lab and diagnostic orders, advance directive observation | Location, Device, ServiceRequest, Observation |
Versions and dates
ONC publishes a new USCDI version each July, but a version becomes required only when a rule adopts it: v1 (2020) was required from the end of 2022 under the Cures Act Final Rule, and v3 (2022) is the baseline from 1 January 2026 under HTI-1. Versions 4 to 6 may be supported early under standards version advancement.
ONC publishes a new version each July after a public submission process; a version becomes required only when a rule adopts it. v1 (2020) was adopted by the Cures Act Final Rule, required from the end of 2022. v3 (2022) was adopted by HTI-1 (January 2024) as the baseline from 1 January 2026, when v1 expired. v4 (2023) added facility information, medical devices, orders and more health-status elements; v5 (2024) and v6 (2025) continued with items such as advance directives, more SDOH and laboratory specimen details. The HTI rules since 2024 adopt newer versions as optional ("standards version advancement") ahead of their required date, so certified products can move early. The equivalence with US Core: v3 ↔ US Core 6.1, v4 ↔ US Core 7, v5 ↔ US Core 8.
USCDI and information blocking
USCDI defined the initial scope of the US information-blocking rules: from April 2021 to October 2022, electronic health information (EHI) was limited to USCDI v1 elements. Since 6 October 2022, EHI means the full designated record set, so USCDI no longer bounds what must be shared, only what certified systems must share in standard form through APIs.
Under the Cures Act rules, actors (providers, certified health IT developers, networks) must not interfere with access, exchange or use of electronic health information (EHI) except under eight exceptions. From April 2021 to October 2022, EHI was limited to the USCDI v1 elements; since 6 October 2022, EHI means the full designated record set in electronic form. USCDI therefore no longer bounds what must be shared; it bounds what certified systems must share in standard form through APIs, which is what apps can rely on.
USCDI+
USCDI+ extends the core for specific programmes and domains with their own data needs: public health reporting, quality measurement, cancer registries, maternal health, behavioural health. Each USCDI+ domain adds elements beyond the core, with the same element definitions and US Core mappings where they exist, so that a specialty registry and a hospital EHR agree on the base.
What it means for a record that consumes US data
A record that consumes US health data through certified APIs or TEFCA individual access receives FHIR US Core resources whose vocabularies are fixed by USCDI: LOINC for laboratory results and vital signs, SNOMED CT and ICD-10-CM for problems, RxNorm for medications, CVX for vaccines and UCUM for units. Such a record targets US Core 6.1 or later.
If your product pulls data from US providers through certified APIs (patient access under the Cures Act rules, or TEFCA individual access), you will receive US Core resources whose shape and vocabularies are fixed by USCDI: LOINC for labs and vitals, SNOMED CT and ICD-10-CM for problems, RxNorm for medications, CVX for vaccines, UCUM for units, LOINC document types for notes. Build to US Core 6.1 or later, handle must-support elements as described in FHIR profiles and extensions, and expect the clinical notes as DocumentReference with embedded or linked content. Map medications from RxNorm to ATC for an international record (RxNorm vs ATC) and keep the US codes alongside.
The European parallel
The EHDS defines priority categories of data (patient summary, ePrescription and eDispensation, medical images and reports, laboratory results, discharge reports) and a European EHR exchange format built on FHIR and the IPS, which plays the role USCDI and US Core play in the US. See Your medical data in the EU and The International Patient Summary.
Anpheros stores US Core resources as received, with provenance, and shows them in the same record as European data; where a US code system has an international counterpart, both are kept.
This page explains regulation for product and engineering teams. It is not legal advice; the texts linked under Sources are the authority, and your data protection officer, notified body or counsel decides for your case. Last reviewed: October 2026.
Related pages
- TEFCA and QHINs explained
- FHIR implementation guides explained
- FHIR profiles and extensions explained
- RxNorm vs ATC
- The International Patient Summary
- Health data regulation map
Sources
- ASTP/ONC: United States Core Data for Interoperability (USCDI)
- HTI-1 Final Rule (Federal Register, January 2024)
- HL7 US Core Implementation Guide
- ASTP/ONC: Information Blocking
- ASTP/ONC: USCDI+
Frequently asked questions
Is USCDI the same as US Core?
No. USCDI lists the data classes and elements (the what); US Core is the HL7 FHIR implementation guide that defines profiles for each (the how). Each US Core version corresponds to a USCDI version.
Which USCDI version must a certified system support now?
Version 3 is the required baseline from 1 January 2026 under HTI-1; newer versions may be supported early under the standards version advancement process. Check the current ONC certification criteria for the exact state.
Does USCDI apply outside the US?
No, but its structure is a useful reference: it is the US answer to the question the EHDS answers with priority categories and the European EHR exchange format. International products map both to the same FHIR record.
Where are images in USCDI?
Only as diagnostic imaging reports (narrative and structured). The images themselves remain in DICOM and are outside USCDI; see the DICOMweb and ImagingStudy pages.
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