Home › Denial Codes › CO-226

CO-226 — Information Requested From the Provider Was Not Provided

The payer asked your practice for something, usually medical records, and did not get it in time. The fix is to send exactly what was asked for, the way the payer wants it.

What CO-226 Means

CO-226 means the payer asked the billing or rendering provider for information and did not get it, got it late, or got too little. The official X12 wording for code 226 is: “Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete.”

The CO group code means a contractual adjustment. The practice cannot bill the patient for it. The good news is that the service itself was not judged unnecessary. The payer simply never saw the proof it asked for, so a CO-226 is often fixable.

What the Payer Usually Asked For

Code 226 always comes with at least one remark code. The remark code tells you what is missing, so read it before you do anything else.

Medical records for the visit. Remark code M127 reads “Missing patient medical record for this service.” This is the most common reason.

Other documentation. Remark code N706 reads “Missing documentation.” Look at the payer's letter or portal for the exact items, such as an order, a certification or test results.

A Medicare documentation request (ADR). Medicare contractors send an additional documentation request before they pay some claims. If no answer arrives in time, the claim is denied.

CO-226 vs CO-252 vs PR-227

	CO-226	CO-252	PR-227
What happened	The payer asked the practice for information and did not get it in time	The claim needs an attachment or other documentation to be processed	The payer asked the patient for information and did not get it
Who has to act	The practice	The practice	The patient, with the practice's help
Can the patient be billed?	No	No	Assigned to the patient, but usually fixable
Usual fix	Send the records, then ask for the claim to be reconsidered or appeal	Send the attachment the way the payer asks	Patient answers the payer, claim is processed again

See the full guides to CO-252 and PR-227. If the claim itself was missing data when you sent it, that is CO-16 instead.

How to Fix a CO-226 Denial

Read the remark code and the request letter. Note what was asked for, the date of the request and where it had to be sent. Many payers show this in their provider portal.

Pull exactly what was requested. For records, include the full note for that date of service, signed and dated, plus any order, test result or certification the service depends on. Unsigned notes are a common reason records are rejected.

Send it the way the payer asks. Use the portal upload, fax cover sheet or mailing address in the request. Medicare also accepts records through its electronic submission program (esMD). Keep proof of the date you sent it.

Ask what happens next. Some payers reprocess the claim once the records arrive. Others need a reconsideration request or an appeal. For a Medicare claim already denied, file a redetermination with the records within 120 days. Our Medicare appeals calculator gives you the exact deadline.

Watch the filing clock. A resubmitted or appealed claim still has to meet the payer's limits. Check the dates in the timely filing calculator before they pass.

How Long You Have to Send Records

For Medicare, providers have 45 calendar days to answer a documentation request from a MAC, RAC, SMRC or CERT reviewer, and 30 days for a UPIC request. If the records do not arrive by then, the reviewer denies the claim. Commercial plans set their own deadline in the request letter, so read it the day it arrives.

A Worked Example

A cardiology practice bills an echocardiogram (93306), which pays $196.73 nationally under the 2026 Medicare fee schedule. The MAC sends a documentation request, but it goes to an old fax number and nobody answers. Forty-five days later the claim denies CO-226 with remark M127. The practice pulls the signed order and the signed interpretation, files a redetermination with both, and updates its address with the MAC so the next request reaches the right person.

How to Prevent CO-226

Keep one log of every records request, with the due date, and give one person the job of answering it.
Check payer portals and mail every week. Many requests arrive by letter, not on the remit.
Keep your mailing address and fax number current with every payer, especially Medicare.
Get notes signed and dated promptly. Unsigned or late-signed records often fail review.
For services that need an order or certification, file it with the note so it goes out together.

Sources

Reason and remark code wording is from the official X12 Claim Adjustment Reason Code and Remittance Advice Remark Code lists. Medicare response times are from the CMS Medicare Program Integrity Manual, Chapter 3 (42 CFR 405.903, 405.929 and 405.930).

Related Denial Codes

CO-252 (attachment or documentation required), PR-227 (patient information not provided), CO-16 (claim lacks information), CO-50 (medical necessity), and all denial codes.

Frequently Asked Questions

What does denial code CO-226 mean?

CO-226 means information the payer requested from the billing or rendering provider was not provided, was late or was incomplete. It usually means medical records the payer asked for never arrived. The CO group code means the patient cannot be billed for it.

What is the difference between CO-226 and CO-252?

CO-252 means the claim needs an attachment or other documentation to be processed. CO-226 means the payer already asked the practice for information and did not get it in time. Both are fixed by sending the documents the payer wants.

Can I bill the patient for a CO-226 denial?

No. CO means a contractual adjustment, so the amount cannot be moved to the patient. Send the requested information and ask the payer to reconsider the claim.

How long do I have to answer a Medicare records request?

Medicare gives providers 45 calendar days to answer a documentation request from a MAC, RAC, SMRC or CERT reviewer, and 30 days for a UPIC. After that, the claim is denied. Commercial plans set their own deadline in the request letter.

Should I appeal or resubmit a CO-226 claim?

Follow the remit and the payer's instructions. Some payers reprocess the claim once the records arrive. For a Medicare claim that was already denied, file a redetermination with the records within 120 days.

Reviewed by Hassan Raza Awan, Founder — 4+ years of hands-on U.S. medical billing experience. General billing information — verify against current CMS guidance and your payer contracts.

Records Requests Turning Into Denials?

We track every payer records request and answer it on time as part of full revenue cycle management. The first week is free.

Get a Free Practice Audit