R56.9
BillableUnspecified convulsions
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is R56.9 an HCC code?
Yes. R56.9 maps to Seizure Disorders and Convulsions under the CMS-HCC V28 risk adjustment model (and Seizure Disorders and Convulsions 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 R56.9
For R56.9 to 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 R56.9 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
R56.9 is the ICD-10-CM diagnosis code for unspecified convulsions. Seizures or convulsions where the specific type or cause has not been determined or documented. R56.9 sits in the ICD-10-CM chapter for symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (r00-r99), within the section covering general symptoms and signs (r50-r69).
Under the CMS-HCC V28 risk adjustment model, R56.9 maps to Seizure Disorders and Convulsions (HCC 201) with a community, non-dual, aged base RAF weight of 0.262. Under the older V24 model, R56.9 mapped to the same category but with a base RAF weight of 0.244 — 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 this code only when the type of convulsion cannot be specified; attempt to obtain more clinical detail. Because R56.9 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 R56.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the type of convulsion cannot be specified; attempt to obtain more clinical detail
- •Review documentation for any indicators of febrile, post-traumatic, or other specific convulsion types
Clinical Significance
Unspecified convulsions represent seizure activity where the specific type, cause, or characteristics have not been determined, indicating need for further neurological evaluation. While less specific, this diagnosis still represents significant neurological symptoms requiring investigation and potential treatment to prevent recurrence and identify underlying causes.
Documentation Requirements
- ✓Documentation of seizure or convulsive activity
- ✓Witness description of episode
- ✓Duration and characteristics if known
- ✓Associated symptoms or triggers
- ✓Neurological examination findings
- ✓Investigations performed or planned
- ✓Response to any interventions
- ✓Follow-up care arrangements