This page is part of the ACCESS Model IG v0.9.8 DRAFT (v0.9.8: Releases Draft) based on FHIR (HL7® FHIR® Standard) R4. No current official version has been published yet. For a full list of available versions, see the Directory of published versions
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| Official URL: https://dsacms.github.io/cmmi-access-model/ImplementationGuide/cms.fhir.us.cmmi-access-model | Version: 0.9.8 | ||||
| Draft as of 2026-05-20 | Computable Name: CMSAccessAPI | ||||
Overview
Welcome to the CMS ACCESS Model API Implementation Guide. This comprehensive guide covers all APIs for the CMS ACCESS (Advancing Chronic Care with Effective, Scalable Solutions) Model.
The ACCESS Model aims to modernize chronic condition management across Medicare by testing a value-based payment system that prioritizes health outcomes, clinical accountability, and patient empowerment. It enables care organizations to use a wide range of technology-supported tools — including virtual care, remote monitoring, digital therapeutics, and coordinated team-based services — that are often difficult to bill under traditional fee-for-service Medicare.
For more information about the CMS ACCESS Model, please see the ACCESS Model website.
About This Implementation Guide
This Implementation Guide (IG) consolidates guidance for all ACCESS Model Application Programming Interfaces (APIs) into a single comprehensive resource, providing:
- Consistent authentication mechanisms
- Shared resources used across multiple APIs
- API-specific resources used in specific APIs
ACCESS Model APIs
This IG covers four primary APIs: the Eligibility API, the Alignment API, the Unalignment API, and the Data Reporting API.
Eligibility API
This API allows participants to quickly determine if a patient meets the basic eligibility criteria for participation in the ACCESS model.
Key Operations:
$check-eligibility- Submit eligibility check request$submission-status- Check status of eligibility request
Learn more about the Eligibility API in the ACCESS API Operations Manual.
Alignment API
This API aligns eligible patients to participants within specific ACCESS Model tracks. When a patient is aligned to an ACCESS Model track, a subscription is created to provide event notifications related to the patient to the participant. This subscription will provide information on the patient’s status throughout the ACCESS Model and provide valuable reminders.
Key Operations:
$align- Submit alignment request$submission-status- Check status of alignment request
Additional Features:
- Subscription-based event notifications
Learn more about the Alignment API in the ACCESS API Operations Manual.
Unalignment API
This API allows a participant to manually unalign a patient from the ACCESS Model track due to specific approved reasons such as patient relocation or loss of contact.
Key Operations:
$unalign- Submit unalignment request$submission-status- Check status of unalignment request
Learn more about the Unalignment API in the ACCESS API Operations Manual.
Data Reporting API
This API allows a participant to submit required data reporting information for patients aligned to the ACCESS Model to support program evaluation and performance measurement.
Key Operations:
$report-data- Submit data report$submission-status- Check status of data submission
Learn more about the Data Reporting API in the ACCESS API Operations Manual.
ACCESS Model Tracks
All APIs support the following ACCESS Model tracks:
- eCKM (Early Cardio-Kidney-Metabolic) - Hypertension, dyslipidemia, obesity, prediabetes
- CKM (Cardio-Kidney-Metabolic) - Diabetes, chronic kidney disease, atherosclerotic cardiovascular disease
- MSK (Musculoskeletal) - Chronic musculoskeletal pain
- BH (Behavioral Health) - Depression and anxiety
Key Features
- Asynchronous Processing - All primary operations are asynchronous, returning a URL with submission ID to check the status
- US Core Alignment - Leverages US Core Patient, QuestionnaireResponse, and Condition profiles
- OAuth 2.0 Security - Enterprise-grade authentication using client credentials flow
- FHIR R4 - Built on FHIR R4.0.1 specification
- Subscription Support - Real-time notifications for ACCESS Model events and deadlines
Getting Started
- Review the Operations Manual - Understand common patterns and requirements across all APIs
- Select Your APIs - Choose the appropriate APIs for your use case
- Review Artifacts - Examine the technical specifications
- Review Conformance Expectations - Understand conformance requirements
Navigation Tips
- Use the top menu bar to access different IG sections
- The Artifacts page provides a comprehensive list of all formal artifacts with links to detailed pages
- Code examples throughout use realistic placeholder URLs marked as
[base]- replace these with your actual API endpoint - All examples show both HTTP headers and JSON bodies separately for clarity
For Different Roles
-
API Developers: Review the Operations Manual for detailed implementation patterns, then examine the operation definitions in Artifacts.
-
Integration Architects: The Operations Manual contains sequence diagrams showing the asynchronous pattern and system interactions.
-
QA/Testing Teams: Use the example instances in Artifacts to understand expected responses for different eligibility scenarios.
-
Compliance/Security Teams: The Operations Manual includes Security Considerations for authentication, TLS requirements, and data handling practices.
FHIR Knowledge Prerequisites
This IG assumes familiarity with:
Core FHIR Concepts:
- FHIR R4 basics including resources, data types, and the RESTful API
- HTTP/REST APIs - RESTful API basics and HTTP status codes
- FHIR Operations - Operations Framework and custom operations
- Parameters for operation inputs and outputs
- FHIR Asynchronous request patterns
US Core Profiles:
- US Core Patient
- US Core Observation profiles
- US Core Blood Pressure
- US Core BMI
- US Core Body Weight
- US Core DiagnosticReport Lab
- US Core Organization
- US Core Practitioner
- US Core QuestionnaireResponse
Additional FHIR Resources/Profiles (for Data Reporting API):
- Bundle resource for document bundles
- Composition resource for organizing clinical data
- Structured Data Capture Base Questionnaire
Security:
- OAuth 2.0 Client Credentials flow for API authentication
- SMART App Launch Backend Services
Credits
These are the contributing organizations which drive the guidance in this IG:
- Centers of Medicare and Medicaid Services (CMS)
- Global Alliant, Inc.
- Firely USA Inc.
For more information contact Dave Hill (david.h[at]globalalliantinc.com).
Globals Profiles
There are no Global profiles defined
Package Dependencies
Package hl7.fhir.uv.extensions.r4#5.2.0 This IG defines the global extensions - the ones defined for everyone. These extensions are always in scope wherever FHIR is being used (built Mon, Feb 10, 2025 21:45+1100+11:00) |
Package hl7.fhir.uv.extensions.r4#1.0.0 This IG defines the global extensions - the ones defined for everyone. These extensions are always in scope wherever FHIR is being used (built Sun, Mar 26, 2023 08:46+1100+11:00) |
Package hl7.fhir.uv.bulkdata#2.0.0 FHIR based approach for exporting large data sets from a FHIR server to a client application (built Fri, Nov 26, 2021 05:56+1100+11:00) |
Package hl7.fhir.uv.sdc#3.0.0 The SDC specification provides an infrastructure to standardize the capture and expanded use of patient-level data collected within an EHR. |
Package ihe.formatcode.fhir#1.1.0 Implementation Guide for IHE defined FormatCode vocabulary. (built Thu, Feb 24, 2022 16:55-0600-06:00) |
Package hl7.fhir.us.core#6.1.0 The US Core Implementation Guide is based on FHIR Version R4 and defines the minimum conformance requirements for accessing patient data. The Argonaut pilot implementations, ONC 2015 Edition Common Clinical Data Set (CCDS), and ONC U.S. Core Data for Interoperability (USCDI) v1 provided the requirements for this guide. The prior Argonaut search and vocabulary requirements, based on FHIR DSTU2, are updated in this guide to support FHIR Version R4. This guide was used as the basis for further testing and guidance by the Argonaut Project Team to provide additional content and guidance specific to Data Query Access for purpose of ONC Certification testing. These profiles are the foundation for future US Realm FHIR implementation guides. In addition to Argonaut, they are used by DAF-Research, QI-Core, and CIMI. Under the guidance of HL7 and the HL7 US Realm Steering Committee, the content will expand in future versions to meet the needs specific to the US Realm. These requirements were originally developed, balloted, and published in FHIR DSTU2 as part of the Office of the National Coordinator for Health Information Technology (ONC) sponsored Data Access Framework (DAF) project. For more information on how DAF became US Core see the US Core change notes. (built Fri, Jun 30, 2023 14:02+0000+00:00) |
Package hl7.fhir.us.carin-bb#2.1.0 CARIN Consumer Directed Payer Data Exchange (CARIN IG for Blue Button®) (built Tue, Feb 18, 2025 17:31+0000+00:00) |
Package hl7.fhir.uv.tools.r4#1.1.2 This IG defines the extensions that the tools use internally. Some of these extensions are content that are being evaluated for elevation into the main spec, and others are tooling concerns (built Tue, Mar 24, 2026 11:13+1100+11:00) |
Cross Version Analysis
This is an R4 IG. None of the features it uses are changed in R4B, so it can be used as is with R4B systems. Packages for both R4 (cms.fhir.us.cmmi-access-model.r4) and R4B (cms.fhir.us.cmmi-access-model.r4b) are available.
Intellectual Property Considerations
This publication includes IP covered under the following statements.
- Copyright (c) 2026 Centers for Medicare and Medicaid Services (CMS).Show Usage
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- This CodeSystem is not copyrighted.Show Usage
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- This material derives from the HL7 Terminology (THO). THO is copyright ©1989+ Health Level Seven International and is made available under the CC0 designation. For more licensing information see: https://terminology.hl7.org/license.htmlShow Usage