CO 261 denial code
Claim adjustment reason code 261. Often reported as CO 261.
Service inconsistent with patient history
Unofficial reference. This is our own plain-English explanation, not the official code text. Payer rules differ. Verify with the payer and the official X12 code list. AlphaPrefix is not affiliated with X12, CMS or any payer. Data last updated .
What 261 means
The payer believes the procedure does not fit the patient's history, such as a service already done or one that cannot be repeated.
The payer compared the claim with what it knows about the patient from earlier claims and found a conflict. Common examples are removing an organ that was already removed, a once in a lifetime service billed again, or a service that does not make sense after a prior procedure.
Sometimes the payer is right, and sometimes earlier claims were coded wrong or the history is incomplete. Look at both before deciding.
Group codes seen with 261
On a remittance, 261 comes after a group code. These are the ones it is most often reported with:
- CO 261 (Contractual Obligation): The provider's side of the ledger. The reduction comes from the payer contract or a rule the provider has to follow, and the patient normally cannot be billed for it.
The payer chooses the group code for each adjustment, so the same reason code can appear with another group code on your remittance. Read the two together. More about group codes.
Common causes
- A procedure that can only be done once was billed again for the same patient.
- A prior claim, possibly from another provider, shows a conflicting procedure.
- A laterality or body site error made the service look like a repeat.
- A previous claim for the patient was coded incorrectly and created a false history.
What to do next
- Review the patient's records to confirm the service was actually done as billed.
- Check modifiers such as RT, LT, or other site modifiers for errors that make the service look repeated.
- Correct and resubmit if there was a coding error, or appeal with notes that explain the clinical history.
- Ask the payer which prior claim caused the conflict if it is not obvious.
Related codes
- 50 (reason code) Not medically necessary per the payer
- N117 (remark code) Once-per-lifetime service
- M86 (remark code) Similar service already paid recently
Source
Official wording: X12 Claim Adjustment Reason Codes list. The explanation on this page is our own plain-English wording, not the X12 text.
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