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N516 Remark Code: NPI and EIN Do Not Match

N516 means the payer's records show a mismatch between the NPI submitted on the claim and the employer identification number (EIN), the federal tax ID. The payer could not confirm that the billing NPI belongs to the tax ID reported, so the claim was denied or rejected.

Code: N516 (RARC N516)
Status: Active In use since March 1, 2009.
Code set: Remittance Advice Remark Codes (RARC)
Group codes: CO (Contractual Obligation): The mismatch is a provider billing or enrollment issue. The patient is not responsible for the adjusted amount.
Official description: Records indicate a mismatch between the submitted NPI and EIN.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified: September 24, 2026 against the official X12 list.

What N516 means

Every payer keeps a provider file that ties each billing NPI to a tax identification number. When a claim comes in, the payer checks the pair. If the EIN in box 25 is not associated with the NPI in box 33a (or in the electronic billing provider fields), the payer cannot confirm who should be paid and to which tax entity the income belongs. N516 is how it reports that failure.

This is almost always an enrollment or setup problem, not a coding problem.

Common causes

A practice changed ownership or tax ID and the payer still has the old EIN.
A provider moved to a new group and is billing under the new group’s EIN, but the payer has not linked the provider to it.
The wrong NPI was used. A group NPI and individual NPI were swapped, or a location’s NPI was used where the organization’s belongs.
Clearinghouse or PM system settings send a default tax ID that does not match the billing entity.

How to fix it

Pull the payer’s provider record through its portal or provider services and see which NPI and tax ID it has linked.
Fix the claim if your system sent the wrong NPI or EIN, then resubmit. Use resubmission code 7 in box 22 if the payer processed the original as a claim; use a new original claim if it was rejected up front.
Update enrollment if the payer’s file is out of date. Submit the change of tax ID, reassignment, or group linkage the payer requires, and ask when it takes effect.
Hold affected claims until the update is confirmed, while watching filing deadlines.
Review other payers. A tax ID change usually needs to be reported to every payer.

How to prevent it

Treat tax ID and NPI changes as enrollment projects with a checklist for every payer. The provider enrollment denials guide covers NPI and TIN linkage in detail, and a Claims Validator check can confirm each claim’s NPI and tax ID pairing before submission.

Codes that may appear with N516

CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim had a billing error; N516 identifies it as an NPI and tax ID mismatch.
CO-208 (National Provider Identifier - Not matched.): The NPI was not matched to the payer's provider records.
CO-B7 (This provider was not certified/eligible to be paid for this procedure/service on this date of service.): Some payers treat the mismatch as the provider not being eligible to be paid for the date of service.

N521 (Mismatch between the submitted provider information and the provider information stored in our system.): Broader mismatch between submitted provider information and payer records.
N209 (Missing/incomplete/invalid taxpayer identification number (TIN).): The taxpayer identification number itself is missing or invalid.
N290 (Missing/incomplete/invalid rendering provider primary identifier.): The rendering provider's primary identifier is missing or invalid.
N433 (Resubmit this claim using only your National Provider Identifier (NPI).): The payer wants the claim resubmitted using only the NPI.

N516 FAQ

Which boxes on the CMS-1500 are involved?

The tax ID is in box 25 and the billing provider NPI in box 33a. The rendering NPI in box 24J can also matter if the payer checks that the rendering provider is linked to the billing tax ID.

Why would a correct NPI and correct EIN still mismatch?

Because the payer links them in its enrollment file. If a provider joined a new group, a practice changed its tax ID, or enrollment was never updated, both numbers can be valid but not linked to each other.

Should I use an SSN instead?

Only if the provider is enrolled with the payer under that SSN. The tax ID on the claim must match the one tied to the billing NPI in the payer's records.

Important: read before using this information

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