Q98.9
BillableSex chromosome abnormality, male phenotype, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is Q98.9 an HCC code?
No. Q98.9 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
Q98.9 is the ICD-10-CM diagnosis code for sex chromosome abnormality, male phenotype, unspecified. A chromosomal condition affecting sex chromosomes in individuals with male physical characteristics, where the specific type of abnormality is not identified. Q98.9 sits in the ICD-10-CM chapter for congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (q00-qa0), within the section covering chromosomal abnormalities, not elsewhere classified (q90-q99).
Q98.9 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.
Use this code only when the specific sex chromosome abnormality cannot be determined; if a specific type is identified (like XXY or XYY), use the more specific code.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Q98.9 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 specific sex chromosome abnormality cannot be determined; if a specific type is identified (like XXY or XYY), use the more specific code
- •Document any associated clinical features or symptoms that may help identify the specific abnormality for future coding refinement