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N688 Remark Code: Reversal From Medical Review

N688 is an alert that the payer reversed an earlier payment because of a medical review or utilization review decision made after the claim was paid. The reviewer's findings decide whether the claim is now denied, reduced, or reprocessed.

Quick facts

Code
N688 (RARC N688)
Status
Active In use since November 1, 2013; last modified March 14, 2014.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The original payment is backed out. If the review found the service not supported, the new adjustment usually falls on the provider.
  • PR (Patient Responsibility): Less common. If the reprocessed claim assigns liability to the patient, confirm that the plan and any notices allow it.
Official description
Alert: This reversal is due to a medical or utilization review decision.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N688 means

A claim that looked finished has been reopened. After payment, a clinical reviewer, whether the payer’s medical review team, a utilization review vendor, or an audit contractor, examined the service and reached a decision that changed the outcome. N688 marks the reversal of the original payment that resulted.

The reversal is often followed by a reprocessed claim showing the new result, which could be a full denial, a lower level of service, or fewer units.

What to do

  1. Get the review findings. The remittance won’t tell you why the reviewer disagreed; the review letter will.
  2. Post the reversal against the original payment and track any recoupment from future payments.
  3. Compare the findings to the record. Look for documentation that answers each point.
  4. Appeal within the deadline if the findings are wrong, including the records and a cover letter.
  5. Look for patterns. If the same service is repeatedly reversed on review, check documentation and coding for that service across your practice.

If the review identified a real problem, correct your processes and consider whether other claims with the same issue should be addressed proactively.

Codes that may appear with N688

  • CO-216 (Based on the findings of a review organization or the payer's findings.): Based on the findings of a review organization or the payer's own review.
  • CO-50 (These are non-covered services because this is not deemed a 'medical necessity' by the payer.): The service was found not medically necessary on review.
  • N661 (Documentation does not support that the services rendered were medically necessary.): Documentation doesn't support medical necessity, a common review finding.
  • N10 (Adjustment based on the findings of a review organization/professional consult/manual adjudication/medical advisor/dental advisor/peer review.): Adjustment based on the findings of a review organization, consultant, or medical advisor.
  • N690 (Alert: This reversal is due to a provider submitted appeal.): A reversal caused by the provider's own appeal, the opposite direction.

N688 FAQ

Can a payer review a claim after paying it?

Yes. Post-payment reviews and audits are common. The time limits for reopening paid claims depend on the payer, contract, and applicable law.

How do I find out what the reviewer decided?

Look for a review letter or request one. It should list the claims affected, the findings, and your appeal rights.

Should I appeal?

If the record supports the service as billed, yes. Respond within the deadline in the review letter and address each finding with documentation.