CO-50 Denial Code: Not Deemed Medically Necessary
Payers publish coverage policies (for Medicare, LCDs and NCDs) describing when a service is reasonable and necessary. CARC 50 means the claim, as billed, did not meet those criteria. Sometimes the service truly did not meet the policy, and sometimes the claim simply did not carry the diagnosis or documentation that shows it did.
Also appears as PR-50. The group code changes who is responsible, not the reason.
CO-50 means the payer decided the service was not medically necessary based on its coverage policy. If the documentation shows the service met the policy criteria, appeal with the records and the policy citation. For Medicare, whether the patient can be billed depends on whether a valid ABN was obtained.
Common causes of CO-50.
- Diagnosis billed is not listed as supporting the service in the coverage policy
- Frequency limits exceeded
- Documentation does not show the required criteria, such as failed conservative treatment
- Service considered experimental or investigational by the payer
How to work a CO-50 denial.
The order matters: confirm the facts before deciding between a corrected claim, a reconsideration, or an adjustment.
- 1Identify the payer's coverage policy for the service and the criteria it requires.
- 2Review the clinical documentation against those criteria.
- 3If criteria were met, appeal with the relevant records and a letter citing the policy language.
- 4If criteria were not met, determine patient liability: for Medicare, a valid ABN (billed with modifier GA) is needed to bill the patient.
- 5Track CO-50 by service and provider to find recurring documentation gaps.
How to keep CO-50 from coming back.
- Check coverage policies before scheduling high-cost or frequently denied services
- Use ABNs correctly for Medicare services likely to be denied
- Obtain prior authorization where the payer offers it
Fixing this at the source usually sits with denial management specialists →
Questions about CO-50.
Denials that often travel with this one.
CO-11: Diagnosis Inconsistent With Procedure
CO-11 means the diagnosis on the claim does not support the procedure billed. What triggers it, how to review pointers and documentation, and how to fix it.
Read about CO-11 →CO-167: Diagnosis Not Covered
CO-167 means the diagnosis on the claim is not covered for the service billed. How to check coverage policy, review documentation, and correct or appeal.
Read about CO-167 →CO-151: Information Does Not Support Frequency or Units
CO-151 means the payer says the information submitted does not support this many services or units. How to check unit limits, documentation, and appeal.
Read about CO-151 →Add a Dedicated Denial Specialist
RCM Staff places trained denial management specialists inside your EHR and clearinghouse to work the queue, correct and appeal claims, and track root causes by payer.
Kevin Jamito has 18+ years of U.S. healthcare revenue cycle management experience across billing, coding, practice management, and offshore RCM operations. He founded RCM Staff to give U.S. healthcare teams dedicated Philippines-based specialists who work inside their existing systems.