CARC CO-15The authorization number is missing, invalid, or does not apply to the...2026 Appeals, Prevention & Recovery Guide
Root Causes
Why CO-15 fires. Understanding the cause is the first step. Fix the cause, not just the symptom.
The authorization number is missing, invalid, or does not apply to the billed services or provider. CO-15 is distinct from CO-197: here an authorization was expected on the claim and the number itself is the problem.
- The authorization number was not entered on the claim
- The number is invalid or contains a transposition error
- The authorization belongs to a different provider or a different service than the one billed
- The authorization does not cover the specific CPT, units, or date of service
Quick Reference
Appeal Strategy
What to attach, what to skip, and where to file. Built from CERT and RAC reports plus major payer manuals.
Confirm a valid authorization exists, then fix the claim:
- Enter the correct authorization number in the right field (the 837 REF*G1 segment, or box 23 on the CMS-1500) and resubmit as a corrected claim
- Verify the authorization matches the rendering provider and the exact service billed
- If the number was valid but mis-keyed, a corrected claim resolves it without a formal appeal
60 percent of denied claims are never resubmitted. That is permanent revenue loss. Our denial management services work every CO-15 line under aging buckets, file appeals within 48 hours, and recover what most billers write off.
Prevention Workflow
The cheapest denial is the one that never fires. Build these checks into the front-end workflow.
Capture the authorization number at scheduling and enter it on every claim that requires one. Verify the number maps to the correct provider and service before submission. Confirm the billing system places the number in the field the payer reads.
Practices that build CO-15 prevention into eligibility, scrubber rules, and charge-capture see 40 to 70 percent reduction in this denial type within 90 days. Catch upstream beats appeal downstream every time.
The cost of denials, in real numbers
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Everything about CO-15
What does denial code CO-15 mean?
The authorization number is missing, invalid, or does not apply to the billed services or provider
Can CO-15 be appealed successfully?
Overturn rate: High when a valid authorization exists and the number is corrected on resubmission. Successful appeals require documentation that directly addresses the payer's stated reason for denial. See the Appeal Strategy section for the exact attachments and modifier paths that win.
How do I prevent CO-15 denials?
Capture the authorization number at scheduling and enter it on every claim that requires one. Verify the number maps to the correct provider and service before submission. Confirm the billing system places the number in the field the payer reads.
CARC codes maintained by X12 N. Overturn rates reflect aggregated CERT, RAC, and payer-published data. Actual results vary by payer, contract, and clinical specifics. Curated content reviewed by AAPC-certified coders.
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