ICD-10-CM 2027 diagnosis code
T78.129DOther adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified, subsequent encounter
T78.129D is a valid, billable ICD-10-CM code for other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified, subsequent encounter. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Other ad food react d/t egg with bkd egg tol/rct, unsp, subs
Code last changed in FY2026 (effective October 1, 2025). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About T78.129D
T78.129D is the ICD-10-CM diagnosis code for other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified, subsequent encounter. It belongs to category T78 (adverse effects, not elsewhere classified), block T66-T78 (other and unspecified effects of external causes) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
The 7th character "D" means subsequent encounter: use it for encounters after active treatment, while the patient is healing or recovering.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 949 (Aftercare with CC/MCC, relative weight 1.123) and DRG 950 (Aftercare without CC/MCC, relative weight 0.7664), in MDC 23 (Factors Influencing Health Status and Other Contacts with Health Services), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
It is exempt from present-on-admission (POA) reporting, so no POA indicator is required.
It was added in FY2026, effective October 1, 2025.
7th character
Dsubsequent encounter
Other encounter types for T78.129:
Notes that apply from higher levels
Instructions written at a parent level also apply to T78.129D.
› From T78.1 Other adverse food reactions, not elsewhere classified
- code to identify the type of reaction, if applicable
Broader instructions also apply from T66-T78 Other and unspecified effects of external causes and Chapter 19: Injury, poisoning and certain other consequences of external causes.
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 23 · Factors Influencing Health Status and Other Contacts with Health Services
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2026 (effective 10/1/2025): Added
- No changes since FY2026.
Common questions about T78.129D
Is T78.129D billable?
- Yes. T78.129D is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
What does the "D" at the end of T78.129D mean?
- It is the 7th character for subsequent encounter. Per the official guidelines, use it for encounters after active treatment, while the patient is healing or recovering.
Can T78.129D be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is T78.129D a CC or MCC?
- No. T78.129D is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does T78.129D group to?
- T78.129D is used in the MS-DRG v44.0 logic for MS-DRG 949 (Aftercare with CC/MCC) and MS-DRG 950 (Aftercare without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.