Question 1

What is ICD-10 code G44.321?

Accepted Answer

G44.321 is the ICD-10-CM diagnosis code for chronic post-traumatic headache, intractable. A persistent headache lasting months or longer that started after a head injury and does not respond well to standard treatments. G44.321 sits in the ICD-10-CM chapter for diseases of the nervous system (g00-g99), within the section covering episodic and paroxysmal disorders (g40-g47).

G44.321 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

Document that symptoms persist for at least 3 months post-trauma to establish chronicity.

Question 2

Is G44.321 an HCC code?

Accepted Answer

No. G44.321 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is G44.321 billable?

Accepted Answer

Yes. G44.321 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. G44.321 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

What is the V28 vs V24 difference for G44.321?

Accepted Answer

G44.321 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards G44.321 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting G44.321?

Accepted Answer

Document that symptoms persist for at least 3 months post-trauma to establish chronicity Ensure documentation clearly indicates failed treatment attempts to justify 'intractable' designation

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G44.321

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G44.321 ICD-10-CM Code: Chronic post-traumatic headache, intractable

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G44.321

Is G44.321 an HCC code?

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Work G44.321 in HCC Buddy