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N793 Remark Code (Deactivated): Medicare MBI Required

N793 was an alert that Medicare would accept only claims with the Medicare Beneficiary Identifier (MBI) and reject claims using the Health Insurance Claim Number (HICN), with limited exceptions. X12 deactivated it after the transition, without naming a replacement.

X12 deactivated RARCN793 on July 1, 2020. Payers should no longer use it on new remittances, but it can still appear on older ERAs, corrected claims, and appeals.

Quick facts

Code
N793 (RARC N793)
Status
Deactivated StoppedJuly 1, 2020 (in use since July 1, 2017).
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): An informational alert; it did not itself shift any amount to the provider or patient.
Official description
Alert: Starting January 1, 2020, Medicare will ONLY accept claims submitted with the Medicare Beneficiary Identifier (MBI). Medicare will reject any claims submitted with the Health Insurance Claim Number (HICN) with a few exceptions. Please see www.cms.gov/Medicare/New-Medicare-Card/index.html for more information.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N793 meant

Remark N793 was a transition alert on Medicare remittances. Medicare replaced the Social Security-based HICN with the Medicare Beneficiary Identifier, and this remark warned providers that, after the cutover, claims would need the MBI to be accepted. It pointed to CMS’s New Medicare Card resources for details.

What replaced it

X12 did not name a replacement, since the alert was about a one-time change. Claims with a missing or wrong beneficiary number are now flagged with identifier remarks such as MA27 or N382, and may be denied with CARC CO-31 when the patient cannot be matched.

If you still see N793

It appears only on remittances from the transition period. For current Medicare claims, always bill with the MBI. If a patient’s number is rejected, verify it with the contractor’s lookup tool, update the patient record, and resubmit.

  • MA27 (Missing/incomplete/invalid entitlement number or name shown on the claim.): Missing, incomplete, or invalid entitlement number or name shown on the claim.
  • N382 (Missing/incomplete/invalid patient identifier.): Missing, incomplete, or invalid patient identifier.
  • CO-31 (Patient cannot be identified as our insured.): Patient cannot be identified as our insured.

N793 FAQ

What is the difference between an MBI and a HICN?

The HICN was the older Medicare number, based on a Social Security number. The MBI is a randomly generated identifier that replaced it on new Medicare cards to protect beneficiaries.

Where do I find a patient's MBI?

On the patient's Medicare card, or through the Medicare contractor's MBI lookup tool in its provider portal.