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N1 Remark Code: Written Appeal Rights Notice

N1 is an informational alert. It tells the provider that the adjudication decision on the claim or line can be appealed in writing, within the required time limits, by following the contract, plan documents, or applicable statutes.

Quick facts

Code
N1 (RARC N1)
Status
Active In use since January 1, 2000; last modified July 1, 2018.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The adjustment is the provider's responsibility under the contract. N1 simply reminds you that a written appeal is available if you disagree.
  • PR (Patient Responsibility): The amount was assigned to the patient. N1 still points to the written appeal route if you believe the patient responsibility is wrong.
Official description
Alert: You may appeal this decision in writing within the required time limits following receipt of this notice by following the instructions included in your contract, plan benefit documents or jurisdiction statutes. Refer to the URL provided in the ERA for the payer website to access the appeals process guidelines.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N1 means

N1 is an alert, not a reason for nonpayment. Payers attach it to a remittance line to let you know that whatever they decided can be challenged through a written appeal. The actual decision is carried by the claim adjustment reason code (CARC) next to it, so N1 always needs to be read together with that code.

The official wording also mentions that the payer’s website address for appeal guidelines may appear in the electronic remittance advice. If your practice management system hides payer contact details, open the raw ERA or the payer’s portal to find it.

What to do

  1. Read the paired CARC first. If the line paid as expected, there is nothing to do.
  2. Decide whether the decision is worth disputing. Compare the outcome to your contract, the documentation, and the payer’s coverage policy.
  3. Rule out a simple correction. If the problem was a billing error on your side, a corrected claim is usually faster than an appeal.
  4. File the written appeal on time. Use the payer’s form or letter format, cite the claim number, explain why the decision is wrong, and attach supporting records.

Tracking which CARCs keep arriving with appeal alerts is one way to spot denial patterns; see how CARC and RARC codes work together.

Codes that may appear with N1

  • CO-50 (These are non-covered services because this is not deemed a 'medical necessity' by the payer.): A medical necessity denial is a common decision providers choose to appeal, and N1 flags that the option exists.
  • CO-96 (Non-covered charge(s).): A non-covered charge adjustment may carry N1 so the provider knows how to contest it.
  • CO-197 (Precertification/authorization/notification/pre-treatment absent.): Missing authorization denials sometimes include N1 alongside the explanation of what was lacking.
  • N210 (Alert: You may appeal this decision.): A shorter alert saying the decision may be appealed, without the written-appeal and URL wording.
  • N211 (Alert: You may not appeal this decision.): The opposite message: this decision cannot be appealed.
  • MA01 (Alert: If you do not agree with what we approved for these services, you may appeal our decision.): Medicare's version of the appeal-rights alert on remittances.
  • N187 (Alert: You may request a review in writing within the required time limits following receipt of this notice by following the instructions included…): Tells you a written review, rather than an appeal, may be requested within time limits.

N1 FAQ

Does N1 mean my claim was denied?

Not by itself. N1 only describes your appeal rights. Look at the CARC on the same line to see whether the service was denied, reduced, or paid.

Where do I find the appeal deadline?

N1 does not state one. The deadline comes from your provider contract, the member's plan documents, or state or federal rules, and the payer may list a website address on the ERA for its appeal guidelines.

Can I appeal by phone?

N1 specifically refers to a written appeal. Some payers offer phone reopenings for simple clerical errors, but check the payer's process before relying on that.