CO-33: Age-Based Service Limitation
CO (Contractual Obligation)What is CO-33?
CO-33 is a Contractual Obligation code indicating the service is limited based on the patient's age. The payer determined the patient falls outside the approved age range for the billed procedure.
Why Does CO-33 Occur?
- Preventive service only covered for specific age groups (e.g., colonoscopy screening covered from age 45+).
- Pediatric service billed for an adult patient or vice versa.
- Age-specific CPT code used for a patient outside the valid age range.
How to Fix CO-33 Denials
- Verify the age requirements for the specific CPT code against the payer's coverage policy.
- If the patient meets the age criteria and the payer's records are incorrect, appeal with proof of the patient's date of birth.
- If the wrong age-specific code was used, correct the CPT code and resubmit.
CO-33 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-33, check these related codes: CO-16 (claim differs), CO-45 (fee schedule), CO-29 (timely filing).
Common Questions About CO-33
What does CO-33 mean?
CO-33 indicates age-based service limitation. Check the RARC code on the EOB for the specific reason and follow the resolution steps above.
Can I appeal a CO-33 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-33 denials before submission with age-based eligibility checking. See how pre-submit claim scoring works.