G30.8
BillableOther Alzheimer's disease
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G30.8 an HCC code?
Yes. G30.8 maps to Dementia, Mild or Unspecified under the CMS-HCC V28 risk adjustment model.
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for G30.8
For G30.8to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed G30.8 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G30.8 is the ICD-10-CM diagnosis code for other alzheimer's disease. Other forms or presentations of Alzheimer's disease that don't fit the typical early or late-onset categories. G30.8 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering other degenerative diseases of the nervous system (g30-g32).
Under the CMS-HCC V28 risk adjustment model, G30.8 maps to Dementia, Mild or Unspecified (HCC 127) with a community, non-dual, aged base RAF weight of 0.464. G30.8 was not retained as a payment HCC under the older V24 model, so V28 introduced or recategorized it during the 2024–2026 phase-in. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code for atypical presentations of Alzheimer's disease; clearly document the specific variant or presentation. Because G30.8 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for G30.8 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code for atypical presentations of Alzheimer's disease; clearly document the specific variant or presentation
- •Ensure that the diagnosis of Alzheimer's disease has been confirmed through appropriate clinical and diagnostic evaluation
Clinical Significance
Other Alzheimer's disease captures atypical presentations that do not fit standard early-onset or late-onset classification, such as posterior cortical atrophy variant or logopenic variant. These patients often present diagnostic challenges and may require more extensive workup. Accurate coding ensures proper resource allocation for these complex neurodegenerative cases.
Documentation Requirements
- ✓Documentation specifying the atypical variant or presentation of Alzheimer's disease
- ✓Cognitive and neuropsychological testing results
- ✓Neuroimaging supporting Alzheimer's pathology pattern
- ✓Clinical rationale for why the case does not fit early-onset (G30.0) or late-onset (G30.1) categories
- ✓Current treatment plan and specialist involvement
Commonly Confused Codes
- •G30.0 — Alzheimer's disease with early onset; use when onset before age 65 is confirmed
- •G30.1 — Alzheimer's disease with late onset; use when onset at age 65+ is confirmed
- •G30.9 — Alzheimer's disease, unspecified; use when no information about onset or variant is available
- •G31.09 — Other frontotemporal neurocognitive disorder; different dementia subtype affecting frontal/temporal lobes
- •G31.83 — Neurocognitive disorder with Lewy bodies; distinct pathology with Lewy body inclusions