ICD-10 G40.843
Billable / Specific HCC v28: 79 CCKCNQ2-related epilepsy, intractable, with status epilepticus
About ICD-10-CM G40.843
ICD-10-CM code G40.843 represents KCNQ2-related epilepsy, intractable, with status epilepticus. This is a billable/specific code in the Nervous System chapter (block G40). The 2026 edition of ICD-10-CM G40.843 became effective on October 1, 2025.
Coding Tips for G40.843
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
G40.843 is a CMS-HCC v28 risk-adjustment code (category 79). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
G40.843 is designated CC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-CC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag CC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, CC
codes KCNQ2-related epilepsy, intractable, with status epilepticus. As a Complication/Comorbidity (CC), this contributes to DRG severity adjustment when documented alongside the principal diagnosis.
Medicare LCD Coverage for G40.843
Local Coverage Determinations (LCDs) from CMS MACs that list G40.843 as a covered diagnosis.
Showing top 10 of 170 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing G40.843.
3 Cigna
5 Medicare
CPT Codes Commonly Billed with G40.843
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Codes Adjacent To G40.843
Other codes in section G40-G47 (Episodic and paroxysmal disorders).
ICD-10 G40.843, Billing FAQ
Is ICD-10 code G40.843 billable? +
Yes, G40.843 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does G40.843 affect Medicare Advantage HCC risk adjustment? +
Yes. G40.843 maps to CMS-HCC v28 category 79. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is G40.843 a CC or MCC for inpatient DRG? +
Yes, this code is designated as CC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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