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N209 Remark Code: Missing or Invalid Tax ID (TIN)

N209 means the taxpayer identification number (TIN) on the claim, either an employer identification number (EIN) or, for some individuals, a Social Security number, was missing, incomplete, or invalid. The payer uses the TIN to identify who gets paid and for tax reporting.

Quick facts

Code
N209 (RARC N209)
Status
Active In use since June 30, 2003; last modified July 1, 2008.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The claim was denied or rejected for bad billing provider data. Correct and resubmit; the patient is not responsible.
Official description
Missing/incomplete/invalid taxpayer identification number (TIN).
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N209 means

Every claim has to say which taxpayer is being paid. The TIN ties the claim to a legal entity the payer has enrolled, whose name is used on 1099 reporting. N209 says that number was not usable: blank, truncated, formatted wrong, or not matching the payer’s file. It commonly explains CARC 16.

Common causes

  • Box 25 was blank or had transposed digits.
  • The SSN box was checked when the number is an EIN, or the reverse.
  • The practice changed ownership or structure and began billing under a new TIN before updating payers.
  • A clearinghouse or practice management system still holds an old TIN for one location.
  • The TIN and legal name do not match IRS records, which payers may check.

How to fix it

  1. Confirm the correct TIN and legal business name from IRS documentation, such as the EIN assignment letter.
  2. Compare it to what the payer has on file for your NPI and group.
  3. Correct box 25 (or the billing provider tax ID in the 837) and resubmit. Front-end rejections usually just need a clean new claim; adjudicated denials may need a corrected claim with resubmission code 7.
  4. If the payer’s file is wrong, update your enrollment before resubmitting.

More on identity mismatches is covered in provider enrollment denials.

How to prevent it

Store the TIN centrally in your billing system and lock it from casual edits. Before any ownership or entity change, plan payer re-enrollment and set a date after which claims move to the new TIN.

Codes that may appear with N209

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim contains a billing error; N209 points to the TIN.
  • CO-B7 (This provider was not certified/eligible to be paid for this procedure/service on this date of service.): The provider was not eligible to be paid, which can surface when the TIN does not match enrollment.
  • MA113 (Incomplete/invalid taxpayer identification number (TIN) submitted by you per the Internal Revenue Service.): An incomplete or invalid TIN as reported by the Internal Revenue Service, with tax withholding implications.
  • N852 (The pay-to and rendering provider tax identification numbers (TINs) do not match): The pay-to and rendering provider TINs do not match.
  • N257 (Missing/incomplete/invalid billing provider/supplier primary identifier.): The billing provider's primary identifier is missing or invalid.

N209 FAQ

Where does the TIN go on a claim?

On the CMS-1500 it goes in box 25, with a checkbox for SSN or EIN. On the UB-04 it is the federal tax number field. Electronic claims carry it with the billing provider.

What makes a TIN invalid?

Wrong digits, the wrong type (SSN instead of EIN), or a TIN that does not match the name and NPI the payer has on file.

Can we use a new TIN right away?

Not until each payer has updated its records. Billing under a new TIN before enrollment is complete often leads to denials.