Medicare Advantage Coding Guidelines

What are Medicare Advantage coding guidelines?

By the HCC Buddy Coding Team · Updated for CY2026 non-PACE CMS-HCC V28 and FY2026 ICD-10-CM

Medicare Advantage coding guidelines are the rules that govern how a risk-adjustment coder captures and validates diagnoses for a Medicare Advantage member. They sit on top of the ICD-10-CM code set rather than replacing it: the code set tells you which characters are valid for a condition, while the guidelines tell you when a diagnosis is supportable, what documentation a chart must contain, and how a specific payer expects the diagnosis to be reported. A coder who knows ICD-10-CM cold can still submit a code that fails a retrospective review because a payer’s guidance required documentation the chart did not have.

Coding guidelines vs the ICD-10-CM code set

The ICD-10-CM code set and Official Guidelines describe code assignment and sequencing. CMS model files identify HCC mappings for a specified model and payment year. Program and payer policies address additional reporting and documentation requirements. Check all applicable sources; a valid code, an HCC mapping and a reportable diagnosis are separate questions.

Categories of payer guidance

Payer guidance for risk adjustment generally falls into three buckets:

• CMS risk-adjustment guidance. The model files, mapping tables, and program rules published by CMS that define the CMS-HCC model itself: which ICD-10-CM codes map to which HCCs, the model and member segments supported by each coefficient table, and the documentation expectations CMS enforces through RADV audits.
• Plan-specific Documents of Understanding (DOUs). Some organizations use a DOU to record agreed coding and documentation expectations. Confirm the actual document’s scope, line of business and effective dates; the term and contents vary.
• Local and plan policies. Plan-level coding policies, claim-edit rules, and condition-specificity requirements that can vary by line of business and document version, and that often go beyond the baseline ICD-10-CM guidance.

What changed for 2026

For CY2026 non-PACE Medicare Advantage, CMS-HCC V28 is fully phased in at 100% of the risk score. PACE uses separate model blends, so the non-PACE rule must not be applied to PACE members. The V24 comparison in HCC Buddy is the historical PY2025 reference, not a second current non-PACE model. That matters for guidelines work because V28 reorganized the HCC hierarchy and remapped conditions relative to the historical model. The prescription-drug side of risk adjustment, the RxHCC model, also continues to be updated by CMS on its own schedule. Coders verifying medicare advantage coding guidelines for 2026 should confirm each rule against the current model year rather than carrying forward last year’s assumptions. CMS publishes the authoritative model files, mapping tables, and program guidance on its Medicare Advantage Risk Adjustment page, which is the source of record for what the model covers in any given payment year.

Where guidelines bite during chart review

Check the source document, effective dates, program and line of business before applying a passage. A search match does not establish that a diagnosis is supported, that an encounter is eligible, or that a rule applies to the record under review. Follow the applicable ICD-10-CM Official Guidelines and CMS program requirements alongside the relevant payer policy.

The encoder searches the public guideline library. Personal payer PDFs are managed separately through Ask Buddy and require sign-in. Upload only documents you are authorized to use, without patient information. Automated screening may reject a document; it does not replace your review of what you upload.

How guideline search speeds up coding

Sources

• CMS CY2026 model software and ICD-10-CM mappings: CMS 2026 model software and ICD-10-CM mappings
• CMS — ICD-10-CM code set: cms.gov/medicare/coding-billing/icd-10-codes