T78.40XD: Allergy, unspecified, subsequent encounter
T78.40XD is a billable, specific ICD-10-CM code for allergy, unspecified, subsequent encounter. It is valid for submission on a claim.
Check T78.40XD with the rest of the claim: free scrubber7th character "D": subsequent encounter
The appropriate 7th character is to be added to each code from category T78
- A
- initial encounter
- D
- subsequent encounter
- S
- sequela
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Allergic reaction NOS
- Hypersensitivity NOS
Excludes1 inherited from the categories above T78.40XD
A category’s note binds every code beneath it.
Written on T78.4: Other and unspecified allergy
Excludes2 inherited from the categories above T78.40XD
Not part of this code, but both may be coded when both are present.
Other codes that can never be billed with T78.40XD
Their own Excludes1 notes name this code, so the conflict is not listed above.
- T75Other and unspecified effects of other external causes
Risk adjustment
No CMS-HCC V28 category: this code does not change a RAF score.
Medicare coverage
T78.40XD is named in 5 Medicare coverage policies: 5 listing it as supporting medical necessity. Which one applies depends on your Medicare contractor.
- A52448Billing and Coding: Omalizumab and biosimilar, OMLYCLO® (omalizumab-igec)
- A56558Billing and Coding: Allergy Testing
- A56844Billing and Coding: RAST Type Tests
- A57361Billing and Coding: Monitored Anesthesia Care
Code history
Unchanged in every release from FY2024 to FY2027.