Diagnosis code __ not valid for patient age.

REJECTION: Diagnosis code specified not valid for patient age.

WHAT HAPPENED: Diagnosis code in box 21 is not valid for the patient date of birth in box 3.

RESOLUTION: Verify the patient’s date of birth and review the ICD-10 code’s age restrictions. If necessary, select a diagnosis code appropriate for the patient’s age, update Box 21, and resubmit the claim.