CO-181 — Procedure code invalid on the date of service
Claim-adjustment reason code 181 · typically reported as CO-181
What it means
The HCPCS billed wasn’t active on the DOS — discontinued, replaced, or not yet effective.
Why DME claims hit it
- Billing a deleted HCPCS after a quarterly update
- New codes used before their effective date
How to fix it
- Check the code’s effective/termination dates and crosswalk to its replacement; update charge masters quarterly
Appeal posture
No — recode and resubmit.
Related denial codes
CO-182 — Modifier invalid on the date of serviceCO-146 — Diagnosis invalid for the date of serviceCO-189 — Unlisted code billed when a specific code exists
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