CO-252 denial code
The payer wants documentation before it will decide. This is not a final denial — it is a request: send the records, and adjudication continues. Treat it like a deadline, because that is what it is; ignored, it hardens into a denial that is much more work to reopen.
CO — Contractual Obligation. The write-off is yours. You agreed to it in your contract with the payer, and you cannot bill the patient for it.
Why you got it
- 1The claim hit a threshold that triggers manual review: high dollar amount, an unlisted or rarely-billed code, or a modifier that promises documentation (22, 25, 59 and friends).
- 2The payer has the provider or the code under a prepayment review program.
- 3An attachment the claim referenced never arrived or never got linked.
How do I fix a CO-252 denial?
- Read the remark codes on the line — they name what is wanted. Send exactly that, not the whole chart.
- Use the payer's stated channel and reference the claim number and any request ID, so the response actually attaches to the claim instead of landing in a general queue.
- Calendar the deadline the moment this arrives. A complete response sent late is the same as no response.
How to stop the next one
Learn which of your codes and modifiers reliably trigger documentation requests, and send the records with the claim. One mailing beats a request-response cycle every time.
Our diagnosis scrubber will not catch this one. CO-252 is driven by procedure codes, modifiers, or eligibility rather than by the diagnosis set — and procedure-side checking needs CPT codes, which aren’t included yet. We would rather tell you that than sell you a tool that quietly misses your most common denial.
If denials like this are a volume problem rather than a one-off, the denial management page explains how the paid workspace catches the coding causes on every claim, and the free ICD-10-CM lookup shows the coding notes behind any diagnosis code on the remittance.
Related denials
- CO-226The payer asked the billing provider for information and considers the answer missing, incomplete, or late.
- PR-227The payer asked the patient for information and never got it, so the claim is denied to the patient.
- CO-16The claim is missing information the payer needs, or something on it is inconsistent.