MCMCB Pro
Z91.13

Z91.13Patient's unintentional underdosing of medication regimen

Non-billable headerICD-10-CM

Z91.13 is a non-billable header ICD-10-CM code for patient's unintentional underdosing of medication regimen. It cannot be billed on its own: choose one of the more specific child codes below.

Code first

The underlying condition must be sequenced before this code.

  • underdosing of medication (T36-T50) with fifth or sixth character 6

Risk adjustment

Z91.13 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.

Code to one of these instead Z91.13

2 child codes. Green means billable.

Related codes at this level

Codes that share Z91.1. If Z91.13 is not quite right, the correct code is usually one of these.

Questions about Z91.13

Is Z91.13 a billable ICD-10-CM code?
No. Z91.13 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
Where does Z91.13 sit in the tabular list?
Factors influencing health status and contact with health services (Z00-Z99), in the block Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99).
ICD-10-CMFY2026-Apr· effective April 1, 2026

Loaded directly from the CMS/NCHS ICD-10-CM public-domain release — see data sources and our editorial policy. If this page disagrees with the CMS tabular list, this page is wrong. Reference information for professional coders; not medical or billing advice.