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Z77.123

Z77.123Contact with and (suspected) exposure to radon and other naturally occurring radiation

Billable / specific codeICD-10-CMPOA exempt

Z77.123 is a billable, specific ICD-10-CM code for contact with and (suspected) exposure to radon and other naturally occurring radiation. It is valid for submission on a claim.

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.

  • radiation exposure as the cause of a confirmed condition (W88-W90, X39.0-)
  • radiation sickness NOS (T66)

Other codes that can never be billed with Z77.123

These codes carry an Excludes1 note pointing at Z77.123. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading Z77.123 alone.

  • X39.0Exposure to natural radiation

Risk adjustment

Z77.123 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

Z77.123 is named in 1 Medicare coverage policy 1 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

  • A56448Billing and Coding: Breast Imaging Mammography/Breast Echography (Sonography)/Breast MRI/Ductography

How Z77.123 is indexed

Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to Z77.123.

  • Contactradiation, naturally occurring NEC
  • Contactradon
  • Exposureradiation, naturally occurring NEC
  • Exposureradon

Related codes at this level

Codes that share Z77.12. If Z77.123 is not quite right, the correct code is usually one of these.

Questions about Z77.123

Is Z77.123 a billable ICD-10-CM code?
Yes. Z77.123 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does Z77.123 sit in the tabular list?
Factors influencing health status and contact with health services (Z00-Z99), in the block Persons with potential health hazards related to family and personal history and certain conditions influencing health status (Z77-Z99).
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.