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N361 Remark Code (Deactivated): Multiple Imaging Rules

N361 meant payment was adjusted based on multiple diagnostic imaging procedure rules. X12 deactivated it and suggested reason code 59, which covers processing under multiple or concurrent procedure rules, including diagnostic imaging.

X12 deactivated RARCN361 on October 1, 2007. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Code: N361 (RARC N361)
Status: Deactivated StoppedOctober 1, 2007 (in use since November 18, 2005).
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): The imaging reduction was a provider write-off under the payer's rules.
Official description: Payment adjusted based on multiple diagnostic imaging procedure rules
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N361 meant

Remark N361 explained a reduction on imaging claims. When a patient had more than one diagnostic imaging study at the same session, the payer applied rules that reduce payment for the additional studies. N361 identified that as the reason the payment was lower.

What replaced it

X12’s note suggested reason code 59. CO-59 says the claim was processed under multiple or concurrent procedure rules and specifically mentions diagnostic imaging. It is separate from the normal fee schedule reduction reported with CO-45. If a study was considered part of another, payers use CO-97.

If you still see N361

It only appears in older remittances. For a current multiple-imaging reduction, verify the studies were on the same patient, date, and session, and that the payer applied the reduction to the lower-valued studies. If studies occurred at separate sessions, report that with the appropriate modifier and documentation.

CO-59 (Processed based on multiple or concurrent procedure rules. (For example multiple surgery or diagnostic imaging, concurrent anesthesia.)): The suggested replacement: processed based on multiple or concurrent procedure rules, for example multiple surgery or diagnostic imaging.
CO-97 (The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.): The benefit is included in the payment for another service.
CO-45 (Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.): Standard fee schedule reduction, separate from the multiple procedure reduction.

N361 FAQ

What are multiple diagnostic imaging rules?

When several imaging studies are done in the same session, payers often pay the highest-valued one in full and reduce payment for the others, since some work is shared.

How do I check a multiple imaging reduction?

Confirm the studies were ranked correctly, that the reduction was applied only to eligible studies, and that separate sessions were not combined in error.

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