US · guidance
CMS Pub. 100-04, ch. 16, § 90.3.2
Medicare Secondary Payer
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.
History
(Rev. 1, 10-01-03)
Provenance
- Source
- cms.gov
- Retrieved
- 2026-08-25
- Edition
- iom-2026-08-25
- Content hash
69a8b10f27bee424320c366b1c72f6a51398f0e53b396138a2050ec6928bd4c5
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