Is T42.3X6D a billable ICD-10-CM code?

Yes. T42.3X6D is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does T42.3X6D 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).

What cannot be coded together with T42.3X6D?

T42.3X6D carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above T42.3X6D (T42.3) and apply to it just the same.

T42.3X6D

T42.3X6D — Underdosing of barbiturates, subsequent encounter

Billable / specific codeICD-10-CMPOA exempt

T42.3X6D is a billable, specific ICD-10-CM code for underdosing of barbiturates, subsequent encounter. It is valid for submission on a claim.

7th character "D" — subsequent encounter

The appropriate 7th character is to be added to each code from category T42

A: initial encounter
D: subsequent encounter
S: sequela

Excludes1 inherited from the categories above T42.3X6D

These are not written on T42.3X6D, but they bind it: a note on a category applies to every code beneath it. Billing T42.3X6D with anything listed here is a denial.

Written on T42.3 — Poisoning by, adverse effect of and underdosing of barbiturates

poisoning by, adverse effect of and underdosing of thiobarbiturates (T41.1-)

Excludes2 inherited from the categories above T42.3X6D

Also inherited, and the opposite of Excludes1: these conditions are not part of T42.3X6D, but a patient can have both, so you may code both.

Written on T42 — Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs

drug dependence and related mental and behavioral disorders due to psychoactive substance use (F10.--F19.-)

Risk adjustment

T42.3X6D 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

T42.3X6D is named in 2 Medicare coverage policies — 2 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A56612Billing and Coding: CT of the Head
A56645Billing and Coding: Controlled Substance Monitoring and Drugs of Abuse Testing

Code history

T42.3X6D has not changed since FY2024 — no addition, revision or deletion across the FY2024–FY2027 ICD-10-CM releases.

Related codes at this level

Codes that share T42.3X6. If T42.3X6D is not quite right, the correct code is usually one of these.

Questions about T42.3X6D

Is T42.3X6D a billable ICD-10-CM code?: Yes. T42.3X6D is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does T42.3X6D 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).
What cannot be coded together with T42.3X6D?: T42.3X6D carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above T42.3X6D (T42.3) and apply to it just the same.