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N909 Remark Code: Non-Standard MFP Refund Method

N909 means the Maximum Fair Price refund on this claim was calculated with a methodology other than the Standard Default Refund Amount, which is the wholesale acquisition cost minus the MFP, times quantity. It is used only in the Medicare Drug Price Negotiation Program.

Quick facts

Code
N909 (RARC N909)
Status
Active In use since March 1, 2025.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): If reported, reflects the difference between the standard default refund and the refund actually calculated. It does not create a patient balance.
Official description
Refund amount has been calculated using a methodology that differs from the Standard Default Refund Amount calculation ((Wholesale Acquisition Cost minus Maximum Fair Price) times Quantity).
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N909 means

For selected Part D drugs, dispensers are made whole for selling at the maximum fair price mainly through manufacturer refunds. The program sets a default formula, but manufacturers may use another method as long as the dispensing entity still effectively receives the MFP.

N909 flags a refund that departs from the default. The amount may be higher or lower than you would compute yourself with list price and MFP.

What to do

  1. Recalculate the standard amount yourself using WAC, MFP, and quantity, to see how far the refund differs.
  2. Request the manufacturer’s methodology if it is not already documented in an agreement with you.
  3. Compare it with your real acquisition cost. The key question is whether the refund leaves you whole relative to what you paid.
  4. Dispute a shortfall through the manufacturer’s process, with invoices showing your purchase price.
  5. Record the method by manufacturer and drug so future refunds can be checked quickly.

Codes that may appear with N909

  • CO-307 (Medicare Maximum Fair Price Standard Default Refund Amount Adjustment.): The standard default refund adjustment; N909 says a different calculation was used.
  • N917 (Alternative refund amount has been calculated because the maximum fair price is below the 340B ceiling price.): An alternative refund calculated specifically because of 340B pricing.
  • N908 (No refund because this drug has been prospectively purchased at the maximum fair price.): No refund at all because the drug was bought at the MFP.
  • N910 (A refund cannot be provided for this claim at this time.): No refund can be provided at this time.

N909 FAQ

What is the Standard Default Refund Amount?

It is the baseline refund: the drug's wholesale acquisition cost minus the maximum fair price, multiplied by the quantity dispensed. It approximates what a pharmacy lost by buying at list price and selling at MFP.

Why would a manufacturer use a different method?

The program allows manufacturers to make the MFP available in other ways, for example a refund based on a different cost measure agreed with the dispensing entity. N909 tells you the standard formula was not used.

How do I check the amount?

Ask the manufacturer for its methodology, then compare it with your actual acquisition cost for the units dispensed.