Look up another code

N356 Remark Code: Not Covered With a Non-Covered Service

N356 means the service is not covered because it was performed together with, or as a follow-up to, a service that is itself not covered. The payer treats related care for a non-covered service as non-covered too.

Code: N356 (RARC N356)
Status: Active In use since August 1, 2005; last modified March 8, 2011.
Code set: Remittance Advice Remark Codes (RARC)
Group codes: PR (Patient Responsibility): When the plan excludes the primary service, related charges are often the patient's responsibility, depending on the plan and any advance notice given.
CO (Contractual Obligation): If your contract or payer rules bar billing the patient without advance notice, the amount stays a provider write-off.
Official description: Not covered when performed with, or subsequent to, a non-covered service.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N356 means

Plans exclude certain services, such as cosmetic procedures or elective treatments outside the benefit. N356 extends that exclusion to the services around it. If anesthesia, lab work, imaging, supplies, or a follow-up visit exists only because of the excluded service, the payer won’t cover those either.

The remark usually accompanies CARC 96 or CARC 204. In routine or preventive contexts, CARC 49 can appear.

Common causes

An excluded primary procedure was billed on the same claim as the anesthesia, facility, or supply charges tied to it.
A post-operative visit was billed after a non-covered surgery.
The diagnosis coding tied a medically necessary service to the non-covered procedure, even though it was clinically separate.
A covered service was performed in the same session, and the payer’s edit applied the exclusion to every line.

What to do

Identify the non-covered service the payer linked to your line. The remittance may show it denied on the same claim or an earlier one.
Decide whether the link is correct. If your service was medically necessary on its own (for example, treating a separate condition in the same session), the documentation and diagnosis pointers in box 24E should show that.
Correct the coding if a diagnosis pointer or modifier wrongly tied the services together, and submit a corrected claim with frequency code 7.
Appeal with records when the service was clearly independent or the plan covers complications.
Bill the patient only where the plan and your notices allow it.

How to prevent it

When scheduling any service a plan may exclude, verify benefits for the whole episode, including anesthesia, facility, and follow-up. Give the patient a written estimate and any required notice for all related charges, not just the main procedure.

Codes that may appear with N356

CO-96 (Non-covered charge(s).): Non-covered charges, the typical reason code for services tied to a non-covered service.
PR-204 (This service/equipment/drug is not covered under the patient's current benefit plan): The service is not covered under the patient's current benefit plan.
CO-49 (This is a non-covered service because it is a routine/preventive exam or a diagnostic/screening procedure done in conjunction with a…): Denies services done with a routine or preventive exam that the plan doesn't cover.

N161 (This drug/service/supply is covered only when the associated service is covered.): The positive version of the rule: this item is covered only when the associated service is covered.
N383 (Not covered when deemed cosmetic.): Used when the service is not covered because it is considered cosmetic.
N431 (Not covered with this procedure.): States the service is not covered with a specific other procedure.

N356 FAQ

What counts as 'subsequent to' a non-covered service?

Follow-up care that exists because of the non-covered service, such as post-operative visits, supplies, or complications management, depending on the payer's policy.

Are complications of a non-covered service always excluded?

Not always. Some plans cover treatment of complications even when the original service was excluded. Read the plan's exclusion language or ask the payer.

Can I bill the patient?

Often yes when the plan excludes the service, but check the payer contract and whether you gave a required advance notice before the service.

Important: read before using this information

This page is general educational information about a standard industry code set. It is not medical billing, coding, legal, reimbursement, or compliance advice, and it does not create a professional or advisory relationship with ClaimsRevenue.

Code definitions, payer usage, contracts, and laws change, and payers may apply the same code differently. The information is provided “as is,” without warranties of any kind, express or implied, including accuracy, completeness, or currency. You are solely responsible for verifying it against the current official X12 code lists, CMS guidance, your payer contracts, and payer policies before relying on it, and for every billing, coding, collection, and appeal decision you make.

Using this information does not guarantee that any claim will be paid or that any appeal will succeed. To the fullest extent permitted by law, ClaimsRevenue and MOODRX LLC are not liable for any loss or damage arising from its use. Official code descriptions are published by X12 and are quoted for reference only. See our full Claims Validation Disclaimer.