Medicare Secondary Payer Payment Calculator

Medicare Secondary Payer Payment Calculator

The MSP payment calculator is intended to provide an approximation of what an MSP payment may be for assigned claims. This calculator does not reflect applicable coinsurance, deductible, or other deductions. MSP claims are calculated line-by-line. Any billing and/or refunds should be done based on your remittance advice and not the results of this calculator.

Here’s what you'll need to get started:

  • Your Billed Amount
  • Medicare Fee Schedule Allowed Amount
  • Primary Insurance Allowed Amount
  • Primary Insurance Paid Amount
  • Obligated To Accept payment in Full (OTAF), if applicable

Note: The OTAF amount will indicate that there is a discount that the beneficiary is not responsible for. To calculate the OTAF, use the primary explanation of benefits, take the billed amount and minus any discounts or adjustments.

Enter the information in the Enter Payment Data fields and select Calculate.

How to Determine the Medicare Secondary Payment Amounts

First, the MSP payment is determined by the following:

  1. Actual charge by physician/supplier or OTAF minus amount paid by primary
  2. Usual Medicare payment determination 
    • Fee Schedule amount (minus any unmet deductible 2024 ‒ $240)
    • Multiply results by 80% (or other as appropriate)
  3. Highest allowed amount minus amount paid by primary
    • MPFS or amount payable under Medicare (not including deductible or coinsurance)
    • Primary payer’s allowed amount

Last, the Medicare payment is the littlest of the three amounts.

Example Calculation
  • Physician’s charges = $175
  • Primary payer’s allowed charge = $150
  • Primary payer paid 80% of allowed charge = $120
  • Medicare fee schedule amount = $125
  • Patient’s Part B deductible met
  1. Actual charge by physician minus primary payer’s payment
    • $175 - $120 = $55
  2. Usual Medicare payment determination
    • 80% x $125 = $100
  3. Highest allowed amount minus amount paid by primary
    • $150 - $120 = $30


Revised 3/6/2024