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N390 Remark Code: Service Can't Be Billed Separately

N390 means the service or report on this line cannot be billed separately. The payer considers it part of another service, so no separate payment is made.

Code: N390 (RARC N390)
Status: Active In use since August 1, 2007; last modified July 1, 2008.
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): Bundled services are a contractual adjustment. The provider cannot bill the patient for the separately billed amount.
Official description: This service/report cannot be billed separately.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N390 means

Payers pay for many services as packages. A procedure’s payment may already include the related report, supply, or minor service. N390 tells you the line you billed falls into that category: it’s covered as part of something else, so the payer won’t pay it on its own.

N390 usually appears with CARC 97, 234, or 236.

Common causes

A report or interpretation that’s part of the primary service was billed as a separate line.
A minor or incidental service performed during a larger procedure was billed separately.
Services from the same session were billed without documentation or a modifier showing they were distinct.
The payer has its own bundling policy that differs from what the practice is used to.
A report requested by a third party was billed to the health plan.

What to do

Identify the primary service the payer bundled your line into.
Check the edit source: NCCI procedure-to-procedure edits or the payer’s own bundling policy. Our NCCI bundling guide explains how these edits work.
Review the documentation. If the service was separate (different session, site, or encounter), and the edit allows a modifier, correct the claim with the right modifier in box 24D and resubmit with frequency code 7.
Appeal when the record supports separate payment but the payer’s edit didn’t consider it.
Write off the line if it really is included, and don’t bill the patient.

How to prevent it

Run claims through bundling edits before submission and teach coders which reports and minor services are included in common procedures. Use modifiers only when the documentation supports a distinct service, and keep payer-specific bundling policies on file for high-volume services.

Codes that may appear with N390

CO-97 (The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.): The benefit for this service is included in the payment for another service already adjudicated.
CO-234 (This procedure is not paid separately.): This procedure is not paid separately.
CO-236 (This procedure or procedure/modifier combination is not compatible with another procedure or procedure/modifier combination provided on the same day…): The procedure or procedure and modifier combination is not compatible with another procedure on the same day.

M15 (Separately billed services/tests have been bundled as they are considered components of the same procedure.): Separately billed services or tests were bundled as components of the same procedure.
N19 (Procedure code incidental to primary procedure.): The procedure code is incidental to the primary procedure.
N20 (Service not payable with other service rendered on the same date.): The service isn't payable with another service rendered on the same date.

N390 FAQ

What kinds of reports are commonly not billed separately?

Reports that are part of a service's normal work, such as the interpretation or write-up included in a procedure's payment, or administrative reports the payer considers overhead.

Can a modifier make the service separately payable?

Only when the service truly was distinct, such as a different session or site, and the payer's rules allow the modifier. Adding a modifier just to bypass an edit is improper.

Is N390 an NCCI edit?

It can result from NCCI edits or from the payer's own bundling policies. The CARC and payer policy will tell you which.

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