CO-252 Denial Code: An attachment/other documentation is required to adjudicate
Not a denial — a documentation request wearing a denial's clothes. The claim is in limbo until you send what they want; ignore it and it silently becomes a write-off.
Why it happens
- Payer wants notes, op report, or itemization before paying
- High-dollar or unusual-code claims flagged for routine review
- Attachment sent but not linked to the claim in the payer's system
- Vague request where the RARC doesn't specify the document
How to fix it, step by step
- Read the RARC remark to identify the exact document requested
- Send it through the payer's specified channel with the claim number on every page
- Diary a follow-up at 30 days — these requests routinely get 'lost'
- If the request is vague, call and get the specific requirement + a reference number
Is it worth working?
Very high — the money is just waiting on paperwork, but only for practices that actually respond.
Very high — the money is just waiting on paperwork, but only for practices that actually respond.
How much is your practice writing off to denials like this?
Send 6 months of remittance files (3 clicks in your billing software) — get a free one-page scorecard of your denied dollars, what's recoverable, and your top payer patterns — within one business day of receiving your files. Recovery is contingency-only: no fee unless money posts.
Get the free denial auditMore codes: the Claimmender denial-code library.