G81.90 ICD-10-CM Code: Hemiplegia, unspecified affecting unspecified side
G81.90 maps to CMS-HCC V28 253. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools
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FY 2026 Apr update / Diseases of the nervous system (G00-G99) / Cerebral palsy and other paralytic syndromes (G80-G83)
G81.90
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceHemiplegia, 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.
Buddy Insight
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.
CMS-HCC V28
MappedHCC 253
Coefficient HCC 253: 0.387 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 150
Code-level coefficient reference
ESRD/PACE
MappedHCC 103
Code-level coefficient reference
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for G81.90. Check the code and parent instructions in the Code Book.
Excludes 2
Official- certain conditions originating in the perinatal period (P04-P96)Inherited from G00-G99
- certain infectious and parasitic diseases (A00-B99)Inherited from G00-G99
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from G00-G99
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from G00-G99
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from G00-G99
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from G00-G99
- neoplasms (C00-D49)Inherited from G00-G99
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from G00-G99
Related Codes
Includes
OfficialNo Includes notes are included in this display for G81.90. Check the code and parent instructions in the Code Book.
Excludes 1
Official- congenital cerebral palsy (G80.-)Inherited from G81
- hemiplegia and hemiparesis due to sequela of cerebrovascular disease (I69.05-, I69.15-, I69.25-, I69.35-, I69.85-, I69.95-)Inherited from G81
Code First
OfficialNo Code First sequencing instructions are included in this display for G81.90. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for G81.90. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for G81.90. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is G81.90 an HCC code?
Yes. G81.90 (Hemiplegia, unspecified affecting unspecified side) maps to HCC 253, Hemiplegia/Hemiparesis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.387. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: G81.90 is billable and maps to V28 HCC 253, Hemiplegia/Hemiparesis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- G81.90
- Description
- Hemiplegia, unspecified affecting unspecified side
- HCC (V28)
- HCC 253 — Hemiplegia/Hemiparesis
- RAF reference coefficient
- 0.387
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work G81.90 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for G81.90
For G81.90, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- 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
Coder workflow notes
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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 source-labeled community, non-dual, aged reference coefficient of 0.387. No V24 mapping is shown for G81.90; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
Use only when type and dominance cannot be determined from documentation. For G81.90, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, 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