How do I resolve a CO-15 denial?

Verify authorization status in payer portal or authorization database: Confirm whether a valid authorization was obtained for the date of service, provider NPI, and specific procedure codes billed Compare claim field 23 (prior authorization number) against payer authorization records: Identify if the number was omitted, contains a typo, or does not match the authorization issued for this member and service Submit corrected claim with accurate authorization number if valid authorization exists: Use claim frequency code 7 and include the correct authorization number in field 23 to reprocess the claim Initiate appeal with authorization documentation if authorization was valid but payer denied incorrectly: Include copy of authorization approval notice, proof it covers the billed services and provider, and dates of service to demonstrate payer error Request retroactive authorization if service was emergent or payer failed to process authorization request timely: Provide clinical documentation supporting medical necessity and proof of timely authorization request submission per contract terms

835 Denial Combination

CO-15

Contractual Obligation · Claim-Level Adjustment

Authorization

What This Combination Means

This combination indicates a contractual denial due to an authorization issue where the authorization number provided is either absent, invalid, or does not match the services or provider billed. The provider is contractually obligated to write off the denied amount and must resolve the authorization discrepancy to obtain payment.

Financial Responsibility

provider writeoff

The provider must write off the denied amount per their contract with the payer and cannot balance bill the patient for this authorization-related denial.

85%

Appeal Success

30-60 days (appeal process)

Avg. Resolution

Hard

Difficulty

Yes

Appealable

Step-by-Step Resolution

Steps tailored specifically to this CO-15 combination — not generic advice.

Appealable:Authorization denials under CO are appealable when valid authorization exists or was obtained but not properly referenced on the claim.

1
Verify authorization status in payer portal or authorization database
Confirm whether a valid authorization was obtained for the date of service, provider NPI, and specific procedure codes billed
2
Compare claim field 23 (prior authorization number) against payer authorization records
Identify if the number was omitted, contains a typo, or does not match the authorization issued for this member and service
3
Submit corrected claim with accurate authorization number if valid authorization exists
Use claim frequency code 7 and include the correct authorization number in field 23 to reprocess the claim
4
Initiate appeal with authorization documentation if authorization was valid but payer denied incorrectly
Include copy of authorization approval notice, proof it covers the billed services and provider, and dates of service to demonstrate payer error
5
Request retroactive authorization if service was emergent or payer failed to process authorization request timely
Provide clinical documentation supporting medical necessity and proof of timely authorization request submission per contract terms

Specialty Context

How CO-15 typically presents across different practice types.

Dental

Common for specialty dental procedures requiring predetermination or authorization such as oral surgery, orthodontics, or TMJ treatment where authorization numbers must match exactly.

Medical

Frequent in surgical procedures, advanced imaging, durable medical equipment, and specialty services requiring prior authorization where NPI, CPT codes, and dates must align with authorization parameters.

Behavioral Health

Applies to outpatient therapy sessions, intensive outpatient programs, partial hospitalization, and inpatient psychiatric admissions requiring authorization with specific session limits or date ranges.

Individual Code References

View the standalone definition for each code in this combination.

CARC 15

Medicare Contractor Guidance for CARC 15

uhc + aetna + bcbs_az

UnitedHealthcare determined that the claim should have been processed based on a referral or authorization that was not in place at the time of service. For certain services or plan types, UHC requires a referral from the member's primary care provider or an approved authorization before the service can be covered. Without this documentation, the claim is denied, and you cannot bill the member.

How to Prevent CARC 15 Denials

✓
Before providing specialty care, verify whether the member's plan requires a referral. Plan design (open access vs. gated vs. tiered) determines referral requirements.
✓
For gated and HMO plans, always obtain a referral from the primary care provider before scheduling specialty services. Submit referral requests via UHCprovider.com > Prior Authorizations.
✓
Confirm the referral is valid (not expired) and includes the specific service or specialty needed. Referrals may be limited to specific dates or service types.
✓
Document referral receipt in the member's medical record. Maintain a copy for billing records and proof of compliance.
✓
For individual exchange plans, verify referral requirements as they may differ from commercial plans. Some individual plans do not require referrals.
✓
Implement a verification process before each visit to confirm referral or authorization is on file. Use UHCprovider.com > Prior Authorizations to check referral status.

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Synthesized from official definitions — not from training data

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