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N936 Remark Code: Secondary Code Under MPPR

N936 means the service was identified as the secondary or tertiary procedure subject to Medicare's Multiple Procedure Payment Reduction (MPPR) rule. It was paid at a reduced amount because it was performed along with a higher-valued service on the same day.

Quick facts

Code
N936 (RARC N936)
Status
Active In use since July 1, 2026.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The MPPR reduction. It is a payment-rule adjustment the provider writes off and cannot bill to the patient.
  • PR (Patient Responsibility): Coinsurance calculated on the reduced allowed amount.
Official description
This service code has been identified as the secondary or tertiary procedure code subject to the Medicare Multiple Procedure Payment Reduction (MPPR) rule.
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N936 means

Medicare assumes that when several related services are performed on the same day, some of the work and practice costs overlap. Under the Multiple Procedure Payment Reduction rule, the highest-valued service is paid in full and the others are paid at a reduced amount. The size of the reduction and the part of the payment it affects depend on the category of service.

N936 labels a service that landed in second or third place. Its companion, N670, marks the primary service that was paid in full.

Common situations

  • Multiple imaging studies in the same session.
  • Several therapy services, or multiple units, on one day.
  • More than one qualifying diagnostic test in the same session.

What to do

  1. Confirm the ranking. The service with the highest payment value should be primary. If a lower-valued code was treated as primary, ask for review.
  2. Check modifiers. Services on different sessions or by different providers may be exempt from reduction when reported correctly.
  3. Post the reduction as a contractual adjustment when it is correct.
  4. Appeal only when the rule was misapplied.

How to prevent surprises

Load MPPR indicators into your fee analysis so expected payments reflect the reduction. See CARC and RARC analysis for tracking payment-rule adjustments separately from denials.

Codes that may appear with N936

  • CO-59 (Processed based on multiple or concurrent procedure rules. (For example multiple surgery or diagnostic imaging, concurrent anesthesia.)): Processed based on multiple or concurrent procedure rules, the reason code that carries the MPPR reduction.
  • CO-45 (Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.): The remaining difference between your charge and the fee schedule amount.
  • N670 (This service code has been identified as the primary procedure code subject to the Medicare Multiple Procedure Payment Reduction (MPPR) rule.): The primary procedure in the MPPR ranking, paid at full value.
  • M80 (Not covered when performed during the same session/date as a previously processed service for the patient.): A service not covered when performed in the same session as another, which is a denial rather than a reduction.
  • CO-97 (The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.): Bundling into another service, rather than a percentage reduction.

N936 FAQ

Which services does MPPR apply to?

Medicare applies MPPR to several categories, including certain diagnostic imaging, therapy services, and some diagnostic cardiovascular and ophthalmology tests. Each category has its own reduction and list of affected codes.

How is the primary procedure chosen?

Medicare ranks the services by their payment value. The highest-valued service is paid in full and the others are reduced.

Is N936 an error?

Usually not. It is expected when multiple qualifying services are billed on the same day. Check that the ranking and reduction match Medicare's rules.