CO-56 denial code
The payer classifies the treatment as unproven, experimental, or investigational for the diagnosis billed.
“Procedure/treatment has not been deemed 'proven to be effective' by the payer.”
Start 01/01/1995 · Last modified 07/01/2017 · X12 adjustment reason code list
What it usually means in behavioral health
CO-56 tends to hit newer or evolving treatments, or established treatments billed for a diagnosis outside the plan's covered indications. TMS billed for a diagnosis the plan's policy doesn't list is a common example.
Common causes
- Diagnosis billed isn't among the covered indications in the payer's policy
- The payer's medical policy classifies the treatment as investigational
- Required prior-treatment history (for example, earlier medication trials) isn't documented
Correct and resubmit, or appeal?
Check the payer's medical policy first. If the diagnosis or history meets the policy, appeal with that evidence. If the policy excludes the treatment, an appeal needs clinical literature and the patient's history. For many plans, denials based on experimental or investigational determinations are eligible for external review once internal appeals are exhausted.
What to do
Pull the payer's current medical policy for the treatment and diagnosis.
Compare the documented diagnosis and treatment history with the policy's criteria.
Appeal with the policy mapping, or with literature if the policy itself is the problem.
After internal appeals, check eligibility for external review.
Often seen with
- N130
- N386
Got a CO-56 on your desk?
Send us the facts on that one denial — codes, payer, level of care, and dollar amount, no patient information — and within 2 business days we’ll tell you whether to correct or appeal, the deadline to watch, and what evidence would answer it. Free.