EOB denial code CO-146: what it means

What it means

The diagnosis code on the claim was not valid for the date the service happened.

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

Official X12 description

“Diagnosis was invalid for the date(s) of service reported”

Typical cause

A diagnosis code that was retired or not yet effective on the date of service — a coding error.

What to do next

1. 1Ask your provider's billing office to verify and correct the diagnosis code for that date.
2. 2Request a corrected claim be resubmitted.