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N591 Remark Code: Paid per IME or Utilization Review

N591 means the payer based its payment decision on an independent medical examination (IME) or a utilization review (UR). The reviewer's findings about necessity, frequency, or duration of care determined what was paid, reduced, or denied.

Quick facts

Code
N591 (RARC N591)
Status
Active In use since July 15, 2013.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The reduction or denial follows the reviewer's findings. In most injury programs the provider cannot bill the patient for it.
  • OA (Other Adjustment): Some carriers use OA when the review affects liability for the injury rather than pricing.
Official description
Payment based on an Independent Medical Examination (IME) or Utilization Review (UR).
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N591 means

Workers’ compensation and auto injury payers often send care for outside review. Utilization review checks treatment against guidelines. An IME is an exam by an independent clinician. N591 tells you that one of these reviews drove the payment decision on this claim.

It is usually paired with CARC 216 (based on review findings), CARC 50 (medical necessity), or CARC P15 (treatment guideline adjustment).

What the review may have found

  • Treatment exceeded guideline frequency or duration for the injury.
  • The patient reached maximum improvement, so further treatment was not supported.
  • Some services were unrelated to the accepted injury.
  • A lower level of care was considered appropriate.

How to respond

  1. Get the review report and read the reasoning, not just the outcome.
  2. Check it against your records. Look for missed documentation, such as objective progress or functional gains.
  3. Submit a rebuttal or request reconsideration with supporting notes, following the jurisdiction’s deadlines.
  4. Adjust the treatment plan or request authorization for further care if the review limits future services.
  5. Post the adjustment correctly if you accept the finding. An ERA analysis makes review-based reductions easier to track across claims.

How to prevent reductions

Document objective measures and functional improvement at each visit, and follow the treatment guidelines the jurisdiction uses. Request authorization before exceeding them.

Codes that may appear with N591

  • 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.
  • CO-50 (These are non-covered services because this is not deemed a 'medical necessity' by the payer.): The reviewer found the service not medically necessary.
  • CO-P15 (Workers' Compensation Medical Treatment Guideline Adjustment.): A workers' compensation medical treatment guideline adjustment.
  • N590 (Missing independent medical exam detailing the cause of injuries sustained and medical necessity of services rendered.): The IME report needed for a decision is missing.
  • N593 (Not covered based on failure to attend a scheduled Independent Medical Exam (IME).): Denied because the patient did not attend the IME.
  • N610 (Alert: Payment based on an appropriate level of care.): Alert that payment was based on an appropriate level of care.

N591 FAQ

What is the difference between an IME and utilization review?

An IME is an in-person examination of the patient by an independent clinician. Utilization review is a records-based review of whether treatment meets guidelines or is necessary.

Can I get a copy of the review?

Often yes. Many jurisdictions require the payer to share the review determination with the treating provider. Ask the adjuster.

How do I dispute the result?

Use the dispute or appeal process set by the payer and the state, such as a request for reconsideration or independent review. Deadlines can be short.