ICD-10-CM > Z00-Z99 > Z77-Z99 > Z91 > Z91.1 > Z91.12 Z91.12 Patient's intentional underdosing of medication regimen Non-Billable/Non-Specific Code First underdosing of medication (T36-T50) with fifth or sixth character 6 Codes Z91.120Patient's intentional underdosing of medication regimen due to financial hardshipZ91.128Patient's intentional underdosing of medication regimen for other reason