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N121 Remark Code: No Part B Payment During Part A SNF Stay

N121 means Medicare Part B does not pay for items or services from this type of practitioner when the beneficiary is in a Medicare Part A covered skilled nursing facility (SNF) stay. The service is expected to be covered through the SNF's payment instead.

Code: N121 (RARC N121)
Status: Active In use since September 9, 2002; last modified August 1, 2004.
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): The practitioner cannot collect from Part B or the patient; payment, if any, comes through the SNF.
Official description: Medicare Part B does not pay for items or services provided by this type of practitioner for beneficiaries in a Medicare Part A covered Skilled Nursing Facility (SNF) stay.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N121 means

When a Medicare beneficiary is in a SNF stay covered under Part A, the facility is paid a daily rate intended to cover most of the care the patient receives. Part B still pays separately for some professional services, but not for all practitioners. N121 tells you that your practitioner type falls on the bundled side of that line for the date of service.

N121 is similar to N106, but it focuses on the practitioner type rather than on who to ask for payment. It often appears with CARC 190 or a provider-type reason code.

Common causes

A therapist, supplier, or other practitioner billed Part B directly for a resident in a covered stay.
The patient moved from a Part A stay to a non-covered stay, but the dates on the payer’s records still show Part A coverage.
The practitioner believed their service was excluded from consolidated billing, but it is not.
Registration did not capture that the patient was a SNF resident.

What to do

Verify the Part A stay dates through the eligibility response or the facility.
Confirm the practitioner type and service against Medicare’s list of services excluded from SNF consolidated billing.
If the stay was not Part A covered, or the service is excluded, request reprocessing or appeal with evidence.
Otherwise, bill the SNF under your arrangement with it. Do not bill the patient.

How to prevent it

If you provide services in nursing facilities, confirm each patient’s coverage status every time you see them, not just at the first visit. Written agreements with the SNFs you serve should cover how bundled services are billed. The eligibility guide describes verification steps that catch facility stays.

Codes that may appear with N121

CO-190 (Payment is included in the allowance for a Skilled Nursing Facility (SNF) qualified stay.): Payment is included in the allowance for a qualified SNF stay.
CO-170 (Payment is denied when performed/billed by this type of provider.): Payment is denied when billed by this type of provider.
CO-171 (Payment is denied when performed/billed by this type of provider in this type of facility.): Payment is denied for this provider type in this type of facility.

N106 (Payment for services furnished to Skilled Nursing Facility (SNF) inpatients (except for excluded services) can only be made to the SNF.): Tells the provider to request payment from the SNF rather than the patient.
N107 (Services furnished to Skilled Nursing Facility (SNF) inpatients must be billed on the inpatient claim.): Requires SNF inpatient services to go on the inpatient claim.
M97 (Not paid to practitioner when provided to patient in this place of service.): Not paid to the practitioner in this place of service because payment is included in the facility's reimbursement.

N121 FAQ

Which practitioners does N121 affect?

Practitioner types whose services are bundled into the SNF's Part A payment, such as many therapy providers, rather than the physician and certain other professional services Medicare excludes from SNF consolidated billing. Check the current exclusion list for the specific provider type and service.

What if the patient's Part A days were used up?

If the SNF stay was not Part A covered on the date of service, N121 should not apply. Show the payer the coverage status and ask for reprocessing.

Can I bill the patient?

No. Bundled services during a covered stay are the SNF's responsibility.

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