Denial Code CO-55: Procedure/Treatment Not Separate
What Does Code 55 Mean?
Procedure/treatment/drug is deemed experimental, investigational, or unproven by the payer. The payer does not consider this an established standard of care.
Group Code CO (Contractual Obligation): The provider has agreed to accept the payer's determination. The patient is generally not responsible for this amount.
Why Does This Happen?
The service or drug is considered experimental or not FDA-approved for this indication.
How to Resolve It
- 1Gather published evidence supporting the treatment
- 2Cite FDA approval status and NCCN or specialty guidelines
- 3Request a peer-to-peer with a specialist medical director
- 4File appeal with supporting literature and case studies
This Denial Is Often Overturned With a Peer-to-Peer Call
When you receive denial code CO-55, the most effective next step is usually a peer-to-peer (P2P) call with the payer's medical director. During this call, you can present your clinical reasoning directly and often get the denial reversed on the spot.
Our free P2P Call Prep Tool generates a structured script based on your specific case, the payer involved, and the denial reason -- so you walk into the call prepared and confident.
Want the full strategy?
The P2P Playbook covers payer-specific approaches for denial code CO-55 -- plus 15 denial objections with word-for-word responses, what reviewers are actually thinking, and the 60-second prep framework. Written by a medical director who reviewed cases for major payers.
Get The P2P Playbook -- $39