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N129 Remark Code: Not Eligible Due to Patient's Age

N129 means the patient was not eligible for the service because of their age. Either the service has an age limit under the plan, or the patient's age places them outside the coverage group for it.

Quick facts

Code
N129 (RARC N129)
Status
Active In use since October 31, 2002; last modified August 1, 2007.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The provider absorbs the amount when an age limit was not checked, unless the patient agreed in advance to pay.
  • PR (Patient Responsibility): The patient may be responsible when the plan excludes the service at that age and the patient accepted the cost.
Official description
Not eligible due to the patient's age.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N129 means

Age drives both coverage and clinical appropriateness. Screening services often start at a set age, some pediatric services stop at one, and dependent coverage usually ends at a set age. N129 tells you the payer compared the patient’s age on the date of service with the rule that applies to the service or to the patient’s coverage, and the patient did not qualify.

Common causes

  • The patient’s date of birth (CMS-1500 box 3) was keyed wrong.
  • The payer has an incorrect birth date on file for the member.
  • A screening was performed before the age at which the plan covers it.
  • A dependent had passed the plan’s dependent age limit.
  • A pediatric-specific service was billed for an adult or the reverse.

How to fix it

  1. Check the date of birth on the claim, in your registration record, and in the payer’s eligibility response.
  2. If the claim was wrong, submit a corrected claim with resubmission code 7 in box 22 and the original claim number.
  3. If the payer’s record is wrong, have the patient or subscriber contact the plan to correct it, then request reprocessing.
  4. If the age rule applies, review the plan’s policy for exceptions and appeal with documentation, or resolve the balance based on the group code.

How to prevent it

Verify date of birth at every registration and compare it with the eligibility response. Build age checks for age-limited services into scheduling or pre-billing edits, and obtain patient acknowledgment of cost when a service is outside the covered age range.

Codes that may appear with N129

  • CO-6 (The procedure/revenue code is inconsistent with the patient's age.): The procedure or revenue code is inconsistent with the patient's age.
  • CO-9 (The diagnosis is inconsistent with the patient's age.): The diagnosis is inconsistent with the patient's age.
  • CO-177 (Patient has not met the required eligibility requirements.): The patient has not met the plan's eligibility requirements.
  • M37 (Not covered when the patient is under age 35.): Not covered when the patient is under age 35.
  • M82 (Service is not covered when patient is under age 50.): Not covered when the patient is under age 50.
  • N906 (Service is not covered when patient is under age 45.): Not covered when the patient is under age 45.

N129 FAQ

What if the date of birth is wrong?

A wrong date of birth on the claim or at the payer is a common cause. Fix it on the claim, or ask the patient to update the payer's records, then resubmit.

Does N129 apply to dependents aging out?

It can. A dependent who has passed the plan's age limit for dependent coverage may be denied on age grounds.

Can the physician override an age limit?

Some payers accept a medical necessity exception with documentation. Check the policy for the service before appealing.