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Claim adjustment reason code

CO-226: Requested information from the provider not supplied

CO-226 means: Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete. At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) The payer asked you for something, and either nothing arrived or what arrived did not answer the question.

Read the group code before you act on this

226 is the claim adjustment reason code. The CO in front of it is the group code — a separate field the payer sets on the remittance. The same reason code arrives under different group codes depending on the payer and the situation, and the group code, not the reason code, decides who owes the money.

CO — contractual obligation. You write it off. You may not bill the patient.
PR — patient responsibility. Billable to the patient.
OA — other adjustment, and PI — payer initiated reduction. Neither is patient responsibility.

What causes it

A records or information request that never reached the person who could answer it
Documentation sent that did not address what was actually asked
Request answered after the payer’s deadline
Response sent to the wrong address, fax or portal

How to work it

Find the original request and read exactly what was asked — most failed responses answered a different question.
Send what was asked, in the channel the payer specified, and record the confirmation.
Where the deadline has passed, ask what the reconsideration route is and its window.
Log the request, the response and the confirmation on the account so a second request does not start from nothing.

How to stop it recurring

Treat payer information requests as a tracked queue with a due date, not as post. This denial is a process failure inside the practice almost every time.

Who does this work

A ar calling & denial management seat at $1,700 per seat per month works this queue full time, during your business hours, inside your own system. Every call is logged with the payer reference number and the outcome, and every Friday you get it in writing.

What that seat does →

Codes worked the same way

CO-226 is answered with the document the payer names. So are these, which is why a queue sorted by recovery route moves faster than one sorted by code number — the same person, in the same system, with the same evidence to hand, clears all of them in one pass.

CO-252 — Additional documentation required
CO-198 — Authorization limit exceeded
CO-227 — Patient did not supply information
CO-251 — Documentation incomplete
N29 — Documentation missing

Specialties that name this among their costliest

These are specialties whose own worst denials include one of this kind. The line under each is the denial they name, quoted from their page so you can see what the link is based on.

Anesthesia
Time units miscalculated from an incomplete anesthesia record
Ophthalmology
Intravitreal injection paid for the administration but not the drug, because the units given and the amount discarded were never written into the note.
Otolaryngology
Endoscopic sinus surgery denied because the chart never pulls the failed medical management together — the drug trials, their dates and imaging findings sit in separate notes or nowhere.
Neurology
Nerve conduction study with needle EMG denied because the report gives only a summary impression instead of each nerve and muscle tested with its findings
Obstetrics & Gynecology
Global maternity package billed in full after the patient transferred care mid-pregnancy, when only the antepartum visits actually rendered here should have been itemised.
Urgent Care
Laceration repair paid at the simplest level because the note says the wound was closed but never records its length, its site or whether the closure was layered

What leaving it costs

Working a denied claim costs $57.23 per denied claim in administrative time. Source. At 100 denials a month — an illustration, not a measurement of your practice — that is $5,723 a month, or $68,676 a year, in labour alone.

The figure that makes it worth spending: about 90% of initially denied claims are eventually paid. Source. The reason a denial sits is almost never that nobody knows how to work it — it is that nobody has the hours.

Questions

What does denial code CO-226 mean?

Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete. At least one Remark Code must be provided (may be comprised of either the NCPDP Reject Reason Code, or Remittance Advice Remark Code that is not an ALERT.) In plain terms: The payer asked you for something, and either nothing arrived or what arrived did not answer the question.

What causes CO-226?

A records or information request that never reached the person who could answer it. Documentation sent that did not address what was actually asked. Request answered after the payer’s deadline. Response sent to the wrong address, fax or portal.

How do you fix a CO-226 denial?

Find the original request and read exactly what was asked — most failed responses answered a different question.. Send what was asked, in the channel the payer specified, and record the confirmation.. Where the deadline has passed, ask what the reconsideration route is and its window.. Log the request, the response and the confirmation on the account so a second request does not start from nothing..

Can CO-226 be prevented?

Treat payer information requests as a tracked queue with a due date, not as post. This denial is a process failure inside the practice almost every time.

Is CO-226 the same as PR-226?

Same reason, different group code. The number 226 is the reason: The payer asked you for something, and either nothing arrived or what arrived did not answer the question. The prefix says who carries the amount. CO means contractual obligation — the payer says the amount is not billable to anybody, and it is written off unless the denial itself is overturned. PR-226 is the same reason assigned to patient responsibility — the payer says the amount is owed by the patient, and it is billed to them. Read the prefix before the number: it decides whether you appeal, write off, or bill the patient.

What is the difference between CO-226 and CO-227?

CO-226: The payer asked you for something, and either nothing arrived or what arrived did not answer the question. CO-227: The payer asked the patient for something — very often about other insurance or an accident — and did not get it. They are different reasons that happen to sit next to each other in the list, and they are worked differently — CO-226 is answered with the document the payer names; CO-227 is answered with the document the payer names.

Code descriptions are the standard X12 claim adjustment reason and remittance advice remark code text. Payer policies differ, and the payer’s own coverage policy governs any individual claim. This page is working guidance, not legal or clinical advice.

Last updated 2026-09-12. This is operational guidance drawn from payer remittance practice, not legal, coding or reimbursement advice. Payer-specific rules vary and change; confirm against the payer’s own policy before acting on a specific claim.

Written by Ibtesam Asif · Last reviewed 2026-09-12

Code descriptions are the standard published text. Everything after them is operational guidance from our own work, and payer policy governs any individual claim.

Other denial codes

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