Medicare Claims Processing Manual (Pub. 100-04), Ch. 16 § 90.3.2
Medicare Secondary Payer
90.3.2 - Medicare Secondary Payer
(Rev. 1, 10-01-03)
When processing claims involving Medicare secondary payer (MSP), A/B MACs (B)
should use the MSP payment formula as follows:
When Medicare is secondary, Medicare pays the lowest of:
•
The actual charge less the primary payment;
•
The amount Medicare would pay if primary; or
•
The higher of the Medicare or primary allowable less the primary payment.
The two-step pricing comparison described above is required for calculating MSP
amounts.