Z91.130 ICD-10-CM Code: Patient's unintentional underdosing of medication regimen due to age-related debility
HCC Buddy Code Card
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FY 2026 Apr update / Factors influencing health status and contact with health services (Z00-Z99) / Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99)
Z91.130
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidancePatient's unintentional underdosing of medication regimen due to age-related debility
An elderly or frail patient unintentionally takes less medication than prescribed due to age-related physical or cognitive limitations, such as difficulty opening bottles or memory problems.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
00
RAF 0
Code Trumping
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for Z91.130 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for Z91.130 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for Z91.130 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for Z91.130 in this effective period.
Code First
Official- underdosing of medication (T36-T50) with fifth or sixth character 6
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for Z91.130 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for Z91.130 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is Z91.130 an HCC code?
No. Z91.130 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
Z91.130 is the ICD-10-CM diagnosis code for patient's unintentional underdosing of medication regimen due to age-related debility. An elderly or frail patient unintentionally takes less medication than prescribed due to age-related physical or cognitive limitations, such as difficulty opening bottles or memory problems. Z91.130 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).
Z91.130 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.
This code requires documentation that the underdosing is unintentional and related to age-related debility.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for Z91.130 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code requires documentation that the underdosing is unintentional and related to age-related debility
- •Consider recommending pill organizers, simplified regimens, or caregiver involvement to improve compliance