What does CO-226 mean?

CO-226 is a Contractual Obligation (CO) denial: "Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete." The payer asked the provider for additional information — records, an itemization, or documentation — and it wasn't supplied, came in late, or was incomplete, so the claim was adjusted.

CO · Contractual ObligationCARC 226

Denial Code CO-226

Q: Is CO-226 the patient's responsibility or a provider write-off?

CO-226 carries the CO group code (Contractual Obligation): Provider/contractual responsibility — not billable to the patient while denied. A CO adjustment is the provider's responsibility, not the patient's: balance-billing the patient for a CO amount is a contract (and often compliance) violation. But CO does not automatically mean “write it off.” When the cause is fixable — missing information (CO-16), a modifier problem (CO-4), or NCCI bundling (CO-97) — you correct and resubmit, or appeal with documentation. You only truly write the amount off when it is a final contractual adjustment, such as the fee-schedule difference on CO-45.

Information requested from the Billing/Rendering Provider was not provided or not provided timely or was insufficient/incomplete.

Source: X12 Claim Adjustment Reason Codes (CARC) & Group Codes. Maintained by the D3rx Clinical Billing Team.

What CO-226 means

The payer asked the provider for additional information — records, an itemization, or documentation — and it wasn't supplied, came in late, or was incomplete, so the claim was adjusted.

Why CO-226 happens

A development/records request from the payer went unanswered or missed its deadline
Documentation was submitted but was partial or insufficient to support the service
The information request was missed in the practice's workflow
Records were sent but didn't include what the payer specifically asked for

What to do when you get CO-226

1Locate the payer's original information request (ERA message or letter) and what it asked for
2Assemble the complete, responsive documentation
3Submit it through the payer's preferred channel, referencing the claim number
4If the records were timely and sufficient, request reconsideration/reopening with proof of the prior submission

Got this denial right now?

Fix & resubmit: see the CO-226 correction steps

See CO-226 correction steps Ask D3 about CO-226

CO-226 clears with a corrected claim, not an appeal. Ask D3 walks you through the exact fix — free, no signup.

CO group code: who absorbs the charge

Contractual Obligation — Provider/contractual responsibility — not billable to the patient while denied.

A CO adjustment is the provider's responsibility, not the patient's: balance-billing the patient for a CO amount is a contract (and often compliance) violation. But CO does not automatically mean “write it off.” When the cause is fixable — missing information (CO-16), a modifier problem (CO-4), or NCCI bundling (CO-97) — you correct and resubmit, or appeal with documentation. You only truly write the amount off when it is a final contractual adjustment, such as the fee-schedule difference on CO-45.

Appeal, correct, or write off CO-226?

CO-226 turns on documentation: provide exactly what was requested and the claim can be reprocessed. At least one remark code accompanies it naming the needed information. Appeal or reopen only when you can show the complete records were submitted on time and the payer overlooked them.

Timing & deadlines

Respond within the payer's documentation deadline (often a short development clock) and inside the overall timely-filing limit (Medicare 12 months from date of service; commercial ~90-180 days). A missed records request typically hardens into a denial, so respond promptly.

Example

A payer requests the office notes for a high-level E/M and the request is overlooked for weeks. The claim posts CO-226 (information not provided timely). Submitting the complete notes with a reconsideration request can still recover payment if you act quickly.

Prevent CO-226 going forward

Build a tracked workflow for payer documentation requests with deadlines
Respond to records requests with complete, responsive documentation the first time
Confirm the payer received the records and the claim re-entered adjudication
Audit recurring requests to fix the upstream documentation gap

Code families most affected

Services subject to medical-record review or development requests
High-dollar E/M and procedures
Claims flagged for itemization or supporting documentation

Related codes

Denial codes you'll often see alongside CO-226

CO-16 CO-252 CO-50

Payer notes

CO-226 concerns information requested from the PROVIDER (contrast PR-227, where the request was to the patient/insured). It is accompanied by a remark code specifying what was needed — read it before responding.

Fix this CO-226 denial the right way

CO-226 is resolved with a corrected claim, not an appeal. Ask D3 gives you the exact correction steps — free, backed by CMS, Medicare, and major-payer data.

See CO-226 correction steps Ask D3 about CO-226 All denial codes

Medical billing disclaimer

CARC/RARC definitions are the standardized X12 set; group-code semantics follow the X12 Claim Adjustment Group Code standard. Filing and appeal windows vary by payer — the standard anchors shown (Medicare redetermination 120 days from the remittance; Medicare timely filing 12 months from date of service; most commercial payers ~90-180 days) are general references, not a guarantee for any specific plan. Always confirm the rule in the payer's provider manual before acting. D3rx is not responsible for claim outcomes.