Question 1

What is ICD-10 code A07.3?

Accepted Answer

A07.3 is the ICD-10-CM diagnosis code for Isosporiasis. Isosporiasis is a parasitic infection of the intestines caused by Isospora organisms, which are spread through contaminated food or water. This condition causes digestive symptoms like diarrhea and abdominal discomfort. A07.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. A07.3 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Question 2

Is A07.3 an HCC code?

Accepted Answer

No. A07.3 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 A07.3 billable?

Accepted Answer

Yes. A07.3 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. A07.3 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

Which HCC does A07.3 map to under V28?

Accepted Answer

A07.3 does not map to a CMS-HCC V28 payment category. Check the current CMS-HCC V28 model file for payment year 2026 rather than an older V24 tip sheet.

Question 5

What does A07.3 pay in RAF?

Accepted Answer

A07.3 has no separately stated V28 community RAF weight. If it is not a V28 payment HCC, it adds nothing to a community RAF score.

Question 6

What is the V28 vs V24 difference for A07.3?

Accepted Answer

A07.3 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 community model rewards A07.3 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's V28/V24 community RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a community payment HCC.

Question 7

What documentation supports A07.3?

Accepted Answer

Isosporiasis is classified as an infectious disease; verify the documentation specifies Isospora as the causative organism to distinguish from other parasitic intestinal infections Consider documenting the severity and any complications (such as malabsorption or dehydration) as these may warrant additional codes and affect treatment intensity A07.3 is not a CMS-HCC payment code, so MEAT is not the payment hook. Documentation still has to support the diagnosis if you report it.

HCC Buddy Code Card

A07.3

Is A07.3 an HCC code?

Get the V28 RAF + MEAT cheat sheet

What This Code Means

Coding Tips

Child Codes

Code Hierarchy

Work A07.3 in HCC Buddy

A07.3 ICD-10-CM Code: Isosporiasis

HCC Buddy Code Card

A07.3

Is A07.3 an HCC code?

Get the V28 RAF + MEAT cheat sheet

What This Code Means

Coding Tips

Child Codes

Code Hierarchy

Work A07.3 in HCC Buddy