T78.120A — Other adverse food reaction due to egg with tolerance to baked egg, initial encounter
T78.120A is a billable, specific ICD-10-CM code for other adverse food reaction due to egg with tolerance to baked egg, 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
Excludes1 — never code together
These conditions cannot occur together. Billing both on the same encounter is a denial.
- Other adverse food reaction due to egg with reactivity to baked egg (T78.121)
Risk adjustment
T78.120A 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
T78.120A is named in 12 Medicare coverage policies — 12 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
- A57531Billing and Coding: Allergy Testing
- A60360Billing and Coding: Allergy Diagnostic Testing
- A60360Billing and Coding: Allergy Diagnostic Testing
Code history
What changed, and when. Derived by diffing consecutive CMS release files — which matters when you are defending a code assigned under an earlier edition.
- addedFY2024-FY2026
Other adverse food reaction due to egg with tolerance to baked egg, initial encounter
Related codes at this level
Codes that share T78.120. If T78.120A is not quite right, the correct code is usually one of these.
Questions about T78.120A
- Is T78.120A a billable ICD-10-CM code?
- Yes. T78.120A is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does T78.120A 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).
- What cannot be coded together with T78.120A?
- T78.120A carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.