CO-6: Procedure Code Inconsistent with Place of Service
CO (Contractual Obligation)What is CO-6?
CO-6 is a Contractual Obligation code indicating the billed procedure code is not payable at the reported place of service. Each CPT code has approved settings (office, facility, telehealth), and billing outside those settings triggers this denial.
Why Does CO-6 Occur?
- Procedure performed in office (POS 11) but only payable in facility setting (POS 21 or 22).
- Telehealth modifier missing. Service delivered via telehealth (POS 02) but billed without the GT or 95 modifier.
- Incorrect POS code selected on the claim form.
- Facility fee billed for a service that only has a non-facility rate.
How to Fix CO-6 Denials
- Verify the correct POS code for the CPT code using the CMS Place of Service Code Set.
- If telehealth, add the appropriate modifier (GT or 95) and the correct POS (02).
- Resubmit with the corrected POS code.
- Appeal if the payer's POS restriction conflicts with state telehealth parity laws.
CO-6 by Payer
| Payer | Common RARC | Appeal Deadline | Notes |
|---|---|---|---|
| UnitedHealthcare | Varies | 60 days from remittance | Reconsideration required before formal appeal. |
| Anthem | Varies | 365 days from denial notice | Check state-specific provider manual for variations. |
| Aetna | Varies | 180 days from denial | Strict in-network filing enforcement. |
| Cigna | Varies | 180 days from denial | Cigna COB team: 1-800-244-6224. |
| Medicare | Varies | 120 days (redetermination at MAC) | Five levels of appeal starting with MAC redetermination. |
Related CARC Codes
If you are seeing CO-6, check these related codes: CO-4 (incompatible coding), CO-97 (bundled service), CO-16 (claim differs).
Common Questions About CO-6
What does CO-6 mean?
CO-6 indicates procedure code inconsistent with place of service. Check the RARC code on the EOB for the specific reason and follow the resolution steps above.
Can I appeal a CO-6 denial?
Yes. Commercial payers allow 60-365 days to appeal depending on the payer. Gather supporting documentation before filing. Medicare allows 120 days for a redetermination request.
Altair catches CO-6 denials before submission with place of service validation. See how pre-submit claim scoring works.