T20 vs T66
T20 (Burn and corrosion of head, face, and neck) compared with T66 (Radiation sickness, unspecified), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. T66 carries an Excludes1 note covering T20: “burns (T20-T31)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| T20Burn and corrosion of head, face, and neck | T66Radiation sickness, unspecified | |
|---|---|---|
| Billing status | Non-billable header Report instead: T20.00XA, T20.00XD, T20.00XS, T20.011A, T20.011D | Non-billable header |
| Classification | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) |
| Definition | Burn and corrosion of head, face, and neck is a non-billable ICD-10-CM category code (T20). | Radiation sickness, unspecified is a non-billable ICD-10-CM category code (T66). |
| 7th character | The appropriate 7th character is to be added to each code from category T20 | The appropriate 7th character is to be added to code T66 |
| Includes | burns and corrosions of first degree [erythema] burns and corrosions of second degree [blisters][epidermal loss] burns and corrosions of third degree [deep necrosis of underlying tissue] [full- thickness skin loss] | — |
| Use additional code | code from category T31 or T32 to identify extent of body surface involved | — |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources