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N77 Remark Code: Invalid Designated Provider Number

N77 means the designated provider number on the claim was missing, incomplete, or invalid. Some payers assign patients to a designated provider, such as a primary care provider or a lock-in provider, and require that provider's number on related claims.

Quick facts

Code
N77 (RARC N77)
Status
Active In use since January 1, 2000; last modified February 28, 2003.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The claim is denied as a correctable billing error. It is not billable to the patient while it can be fixed.
  • PI (Payer Initiated Reduction): Some government programs, including Medicaid, report it as a payer-initiated adjustment.
Official description
Missing/incomplete/invalid designated provider number.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N77 means

Some payer programs tie each member to a particular provider. In managed care, that may be an assigned primary care provider who coordinates care and issues referrals. In Medicaid lock-in programs, it may be a designated prescriber or pharmacy. When the payer requires that provider’s number on claims, and the number is missing or does not match, it returns N77.

N77 is most often paired with CARC 16. If the payer interprets the problem as an unauthorized out-of-network or non-PCP service, CARC 242 or CARC 243 may appear.

Common causes

  • The referring or PCP field was left blank on a specialist claim.
  • The patient’s assigned provider changed and the old number was used.
  • The individual NPI was used where the payer expects its own provider ID, or the reverse.
  • The patient is in a restriction program the office did not know about.

How to fix it

  1. Check eligibility for the designated provider on the date of service.
  2. Obtain the referral or confirmation from the designated provider if one was required.
  3. Enter the number in the payer-specified field, often the referring provider fields on a CMS-1500 (box 17 and 17b) or a payer-specific field.
  4. Submit a corrected claim with resubmission code 7.

How to prevent it

At scheduling, check whether the patient has an assigned PCP or lock-in provider and whether a referral is needed. Store the designated provider’s details in the patient account so they flow onto claims automatically.

Codes that may appear with N77

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): Required information is missing; N77 identifies the designated provider number.
  • CO-243 (Services not authorized by network/primary care providers.): Services were not authorized by network or primary care providers.
  • CO-242 (Services not provided by network/primary care providers.): Services were not provided by network or primary care providers.
  • N778 (Missing Primary Care Physician Information.): Primary care physician information is missing.
  • N27 (Missing/incomplete/invalid treatment number.): A different payer-assigned number, the treatment number, is missing or invalid.
  • N52 (Patient not enrolled in the billing provider's managed care plan on the date of service.): The patient was not enrolled in the billing provider's managed care plan.

N77 FAQ

What is a designated provider?

The official text does not define it further. It commonly refers to a provider the patient is assigned to, such as a primary care provider in a managed care plan or a provider in a Medicaid lock-in or restriction program. Ask the payer if its meaning is unclear.

Where do I find the designated provider number?

Eligibility responses and payer portals often show the assigned provider. The patient's ID card may list a primary care provider as well.

What if the designated provider referred the patient to me?

Report the designated provider in the field the payer requires, often the referring provider fields. Include any referral number the payer issued.