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N329 Remark Code: Missing or Invalid Patient Birth Date

N329 means the payer could not accept the patient's birth date on the claim. It was blank, incomplete, in the wrong format, or did not match the member record, so the payer could not identify the patient or apply age-based edits.

Quick facts

Code
N329 (RARC N329)
Status
Active In use since December 2, 2004.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): A correctable demographic error. The provider must fix the date of birth and resubmit; the amount is not the patient's responsibility.
Official description
Missing/incomplete/invalid patient birth date.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N329 means

The patient’s date of birth is one of the few identifiers payers use on every claim. It confirms the member match and drives age-based edits for screenings, pediatric services, and newborn coverage. N329 says the birth date you sent could not be used, whether because it was missing, partial, formatted wrong, or different from what the plan has on file.

N329 most often explains CARC 16. When the birth date is wrong in a way that trips a clinical edit, it can also appear with CARC 6 or CARC 14.

Common causes

  • A typo at registration, such as a transposed month and day or the wrong year.
  • A newborn billed with a placeholder date, or with the mother’s birth date.
  • The patient’s birth date entered as the subscriber’s, or the reverse, when the patient is a dependent.
  • The plan’s enrollment record has a different date than the patient’s ID or driver’s license.
  • Data that was converted between systems lost part of the date.

How to fix it

  1. Check the source. Compare the claim to the patient’s photo ID and insurance card, and run a real-time eligibility check that returns the date of birth on file.
  2. Correct box 3 (or the 837P patient demographics). If the patient is a dependent, confirm that the subscriber’s date was not placed in the patient’s field.
  3. Resolve enrollment mismatches. When the claim is right but the payer is wrong, the member or employer usually has to update the enrollment file.
  4. Resubmit. Send a corrected claim with resubmission code 7 in box 22 and the original claim number. If the claim was rejected, it was never adjudicated, so send a new claim. See claim rejection vs denial for the difference.

How to prevent it

Scan the ID and insurance card at every new registration and confirm the date of birth verbally at check-in. Run eligibility before the visit and compare the returned date with your record. A pre-submission edit in Claims Validator can flag birth dates that conflict with age-specific services before the claim leaves your office.

Codes that may appear with N329

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim has missing or invalid information; N329 points to the patient's date of birth.
  • CO-140 (Patient/Insured health identification number and name do not match.): The patient's ID and name do not match; a wrong birth date often shows up in the same mismatch.
  • CO-6 (The procedure/revenue code is inconsistent with the patient's age.): The service is inconsistent with the patient's age, which can happen when the birth date on the claim is wrong.
  • N340 (Missing/incomplete/invalid subscriber birth date.): Used when the subscriber's birth date, not the patient's, is the problem.
  • N382 (Missing/incomplete/invalid patient identifier.): Used when the patient's member identifier is missing or invalid.
  • CO-14 (The date of birth follows the date of service.): Denies a service because the reported birth date falls after the date of service.

N329 FAQ

Where does the patient's date of birth go on a CMS-1500?

Box 3, along with the patient's sex. On the electronic 837P it sits in the patient or subscriber demographic information, depending on whether the patient is the subscriber.

The birth date on the claim is correct. Why was it denied?

The payer's enrollment file may have a different date. Ask the patient to contact the plan or employer to correct enrollment, then resubmit once the payer's record is fixed.

Is N329 a rejection or a denial?

It can be either. Many clearinghouses and payers catch a bad birth date at the front end, while others process the claim and deny it with N329 on the remit.