MCMCB Pro
T45.AX6A

T45.AX6AUnderdosing of immune checkpoint inhibitors and immunostimulant drugs, initial encounter

Billable / specific codeICD-10-CM

T45.AX6A is a billable, specific ICD-10-CM code for underdosing of immune checkpoint inhibitors and immunostimulant drugs, initial encounter. It is valid for submission on a claim.

7th character "A" — initial encounter

The appropriate 7th character is to be added to each code from category T45

A
initial encounter
D
subsequent encounter
S
sequela

Risk adjustment

T45.AX6A 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.

Medicare coverage

T45.AX6A is named in 3 Medicare coverage policies 3 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A57473Billing and Coding: Allergy Testing
  • A57473Billing and Coding: Allergy Testing
  • A57657Billing and Coding: Sedimentation Rate, Erythrocyte

Related codes at this level

Codes that share T45.AX6. If T45.AX6A is not quite right, the correct code is usually one of these.

Questions about T45.AX6A

Is T45.AX6A a billable ICD-10-CM code?
Yes. T45.AX6A is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does T45.AX6A sit in the tabular list?
Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50).
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.