Question 1

What is ICD-10 code Z91.013?

Accepted Answer

Z91.013 is the ICD-10-CM diagnosis code for allergy to seafood. A person has an allergic reaction to seafood such as fish, shellfish, or other sea creatures. Z91.013 sits in the ICD-10-CM chapter for factors influencing health status and contact with health services (z00-z99), within the section covering persons with potential health hazards related to family and personal history and certain conditions influencing health status (z77-z99).

Z91.013 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 specific type of seafood (fish, shellfish, crustaceans, mollusks) when possible.

Question 2

Is Z91.013 an HCC code?

Accepted Answer

No. Z91.013 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 Z91.013 billable?

Accepted Answer

Yes. Z91.013 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. Z91.013 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 Z91.013?

Accepted Answer

Z91.013 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 Z91.013 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 Z91.013?

Accepted Answer

Document specific type of seafood (fish, shellfish, crustaceans, mollusks) when possible Note severity of reactions and whether cross-reactivity with other seafood exists

Z91.013

Is Z91.013 an HCC code?

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Open Z91.013 in the Interactive Encoder