EOB denial code CO-50: what it means

What it means

The insurer decided this service was not medically necessary under your plan's criteria, so it was not covered.

Contractual Obligation — an adjustment the provider agreed to by contract. The patient is generally not billed for CO amounts.

Official X12 description

“These are non-covered services because this is not deemed a 'medical necessity' by the payer”

Typical cause

The documentation submitted did not, in the insurer's view, establish medical necessity — sometimes because records were incomplete.

What to do next

1. 1Medical-necessity denials are frequently appealable. Request the insurer's specific medical-necessity criteria.
2. 2Ask your provider to submit supporting clinical documentation and a letter of medical necessity.
3. 3File an internal appeal with your plan; if upheld, you may be entitled to an external review.