MCMCB Pro
T78.05XA

T78.05XAAnaphylactic reaction due to tree nuts and seeds, initial encounter

Billable / specific codeICD-10-CM

T78.05XA is a billable, specific ICD-10-CM code for anaphylactic reaction due to tree nuts and seeds, 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 T78

A
initial encounter
D
subsequent encounter
S
sequela

Excludes2 — not included here, but may coexist

The excluded condition is not part of this code, but a patient can have both. You may code both.

  • anaphylactic reaction due to peanuts (T78.01)

Risk adjustment

T78.05XA 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

T78.05XA is named in 26 Medicare coverage policies 26 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A56558Billing and Coding: Allergy Testing
  • A56558Billing and Coding: Allergy Testing
  • A56558Billing and Coding: Allergy Testing
  • A56612Billing and Coding: CT of the Head

Related codes at this level

Codes that share T78.05. If T78.05XA is not quite right, the correct code is usually one of these.

Questions about T78.05XA

Is T78.05XA a billable ICD-10-CM code?
Yes. T78.05XA is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does T78.05XA sit in the tabular list?
Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Other and unspecified effects of external causes (T66-T78).
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.