Coordination of Benefits & Medicare Secondary Payer

Coordination of benefits: what the secondary payer pays under the chosen method (lesser-of, come-out-whole, etc.) and the patient residual after both payers.

Open the tool → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.

Example

COB method: Lesser-of (standard COB)
Billed charge: 1000 $
Primary allowed amount: 600 $
Primary paid amount: 480 $
Secondary allowed amount: 500 $
What the secondary would pay as primary: 400 $

Result: Lesser-of: secondary pays $120.00, patient residual $0.00 (balance after primary $120.00).

The tool opens with these values already filled in. Replace them with your own.

What you enter

COB method
Billed charge
Primary allowed amount
Primary paid amount
Secondary allowed amount
What the secondary would pay as primary

How this is calculated

42 CFR Part 411 and CMS Pub. 100-05 (Medicare Secondary Payer Manual): the coordination-of-benefits methods (lesser-of, come-out-whole, non-duplication) and the MSP calculation. The patient share after the primary is the primary allowed minus the primary payment. Read the source ↗

A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.