CO-50 denial code
The payer decided the service wasn't medically necessary under the criteria it applied.
“These are non-covered services because this is not deemed a 'medical necessity' 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-50 is the core behavioral health denial. A reviewer concluded the level of care, intensity, or duration wasn't supported: IOP could be routine outpatient, or residential could be PHP.
It is a clinical determination, so it gets appealed, not corrected. The appeal succeeds or fails on whether the record answers the specific criteria the payer used.
Common causes
- Documentation doesn't connect symptoms and functional impairment to the requested intensity
- The record doesn't show why a lower level of care was insufficient or was tried and failed
- The payer applied its own level-of-care guideline, and the record answers a different one
- Templated or cloned notes that hide progress and risk
- No concurrent-review documentation for the denied dates
Correct and resubmit, or appeal?
Appeal. Ask for the specific criteria and guideline version the reviewer relied on, then answer each criterion with dated documentation. For plans the federal parity rule covers, the medical-necessity criteria for mental health and substance use benefits must be made available on request. Use a peer-to-peer review if the plan offers one and it is still within its window.
What to do
Get the denial notice and the criteria relied on; request them in writing if they weren't included.
Calendar the appeal deadline and check whether expedited review applies.
Offer a peer-to-peer review if the plan allows it.
Answer each criterion with a dated finding and an exhibit page (see the appeal letter template).
Track outcomes by payer and level of care; repeated CO-50s from one payer are a documentation and contracting signal.
Often seen with
- N130
- N115
- N386
Got a CO-50 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.