Denial Code B15 — Missing or Invalid Authorization — What It Means and What to Do

Denial Code B15 means an authorization number was missing or wrong. Usually correctable at the billing level if you act fast.

[Alex Rivera

Appeals Specialist and Author](/team/claimcompass)

4

min. read

June 24, 2026

What Does Denial Code B15 Mean?

Denial code B15 means the claim was denied because the prior authorization number was missing, invalid, or did not match the service that was billed. This is related to — but distinct from — CO-4, which denies because authorization was never obtained. B15 specifically addresses situations where an authorization existed but was not correctly applied to the claim.

Why B15 Denials Happen

• The authorization number was omitted from the claim when submitted
• The authorization number was entered incorrectly — transposed digits or wrong format
• The authorization was obtained for a different procedure code than what was billed
• The authorization was obtained for a different date of service than what was performed
• The authorization was obtained for a different provider than who rendered the service
• The authorization has expired

How to Resolve a B15 Denial

B15 denials are often correctable at the billing level. Contact your provider's billing office immediately:

• Confirm the authorization number that was obtained
• Confirm the procedure code, date, and provider the authorization covers
• If the claim was submitted with an incorrect or missing authorization number, correct and resubmit
• If the authorization covers a different code or date than what was performed, contact the insurer to request an authorization amendment
• If the authorization expired before the service was rendered, request an extension or new authorization retroactively with clinical documentation

How ClaimCompass Helps

ClaimCompass analyzes your B15 denial and helps you identifythe correct path — whether that is a corrected claim or a formal appeal.

Upload your denial at myclaimcompass.ai for a free analysis.

Frequently Asked Questions

Who is responsible for tracking authorization numbers?

Your provider's office is typically responsible for obtaining, tracking, and correctly applying authorization numbers to claims. If the authorization was obtained but the number was submitted incorrectly, the billing office can usually correct this.

What if the service was performed under a differentcode than what was authorized?

Contact the insurer and request an amendment to the existing authorization or a retroactive authorization for the actual service performed. Provide clinical documentation supporting why the service performed was equivalent to or covered by the original authorization.

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