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N780 Remark Code: End Therapy Date Missing or Invalid

N780 means the end therapy date on this claim was missing, incomplete, or invalid. Payers use it to know when a course of treatment or equipment use stopped, so they can check the billed period and apply coverage rules.

Quick facts

Code
N780 (RARC N780)
Status
Active In use since November 1, 2016.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The claim needs correction by the provider or supplier. Not patient responsibility.
Official description
Missing/incomplete/invalid end therapy date.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N780 means

Some services are billed as a period of therapy rather than a single encounter. For those, payers may track a begin therapy date and an end therapy date to understand how long treatment lasted. N780 means the end date was absent, incomplete, or failed validation.

It usually pairs with CARC 16. The underlying service may be payable once the date is corrected.

Common causes

  • Therapy stopped, but the billing system never recorded a stop date.
  • The end date was entered before the begin date or outside the claim’s service period.
  • The date format did not match what the payer expects.
  • The date was entered in a claim field the payer does not read for this purpose.

How to fix it

  1. Confirm when the therapy or equipment use actually ended from the clinical record or delivery and pickup records.
  2. Check that the end date is on or after the begin therapy date and consistent with the service dates in box 24A.
  3. Enter the date where the payer requires it and in the required format.
  4. Submit a corrected claim with resubmission code 7.

How to prevent it

Record discontinuation dates as part of the clinical or delivery workflow, and add a claim edit that requires an end date when the payer calls for one. For rental items, reconcile pickup dates with the last billed period.

Codes that may appear with N780

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information, here the end therapy date.
  • CO-A1 (Claim/Service denied.): A general denial explained by the date problem.
  • N312 (Missing/incomplete/invalid begin therapy date.): The begin therapy date is missing or invalid, the other end of the period.
  • N344 (Missing/incomplete/invalid Transcutaneous Electrical Nerve Stimulator (TENS) trial end date.): The TENS trial end date is missing or invalid, a device-specific version.
  • M125 (Missing/incomplete/invalid information on the period of time for which the service/supply/equipment will be needed.): The period of time the service or equipment will be needed is missing or invalid.

N780 FAQ

Which claims need an end therapy date?

Payers may require it for rentals and therapies billed over a period, such as some durable medical equipment, infusion or drug therapies, and certain rehabilitation services. The payer's instructions define when it is required.

What makes an end therapy date invalid?

Common problems are a date before the begin therapy date, a date after the claim's service dates, or a date in the wrong format.

What if therapy is ongoing?

Follow the payer's instructions. Some do not expect an end date until therapy stops; others ask for the end of the billed period.