G81.90
BillableHemiplegia, unspecified affecting unspecified side
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is G81.90 an HCC code?
Yes. G81.90 maps to Hemiplegia/Hemiparesis under the CMS-HCC V28 risk adjustment model (and Hemiplegia/Hemiparesis under V24).
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 G81.90
For G81.90to 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 G81.90 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
G81.90 is the ICD-10-CM diagnosis code for hemiplegia, unspecified affecting unspecified side. Weakness or loss of movement affecting one side of the body where the specific type (flaccid or spastic) and which side is dominant are not specified or documented. G81.90 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering cerebral palsy and other paralytic syndromes (g80-g83).
Under the CMS-HCC V28 risk adjustment model, G81.90 maps to Hemiplegia/Hemiparesis (HCC 253) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, G81.90 mapped to the same category but with a base RAF weight of 0.447 — V28 recalibrated weights across the entire model. 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 only when type and dominance cannot be determined from documentation. Because G81.90 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 G81.90 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use only when type and dominance cannot be determined from documentation
- •Query provider for more specific information when possible to allow for more precise coding
Clinical Significance
Unspecified hemiplegia affecting an unspecified side is the least specific hemiplegia code, indicating significant documentation gaps regarding both the type of muscle tone abnormality and the side affected. While this code still captures the diagnosis for risk adjustment, it represents a prime opportunity for provider query to improve specificity. Hemiplegia patients require substantial ongoing care regardless of the level of coding detail.
Documentation Requirements
- ✓Documentation of hemiplegia or hemiparesis
- ✓Clinical evidence supporting the diagnosis (weakness, functional limitations)
- ✓Underlying etiology when known
- ✓Functional impact on daily activities
- ✓Active treatment or monitoring plan
Commonly Confused Codes
- •G81.00 Flaccid hemiplegia, unspecified side — use when flaccid type is documented
- •G81.10 Spastic hemiplegia, unspecified side — use when spastic type is documented
- •G81.91-G81.94 Unspecified hemiplegia with laterality — use when at least side/dominance is documented
- •R41.89 Other symptoms involving cognitive functions — do not confuse hemiparesis with cognitive deficits