Primary vs Secondary Insurance Calculator accuracy and testing

Formula source

• Secondary payment applied = min(secondary payment, primary patient responsibility). Remaining patient responsibility = primary patient responsibility - secondary payment applied. Combined insurance payment = primary payment + secondary payment applied.

Test cases

Known limitations

• This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
• Use the result as a planning estimate unless the calculator page states a stricter purpose.

Assumptions

• Secondary payment is applied only against the primary patient responsibility entered.
• Coordination order, non-duplication rules, carve-outs, denials, and Medicaid or Medicare-specific rules are not inferred.
• The calculator does not determine which payer is primary or whether a secondary payer should pay.
• Inputs are processed locally in your browser and are not uploaded, stored, or transmitted.
• The calculator uses deterministic arithmetic only and does not infer plan benefits, eligibility, coverage, network status, payer edits, or medical necessity.

Unit handling

• Allowed Amount accepts values in $.
• Primary Insurance Payment accepts values in $.
• Primary Patient Responsibility accepts values in $.
• Secondary Insurance Payment accepts values in $.
• Remaining Patient Responsibility is displayed as currency.
• Secondary Payment Applied is displayed as currency.
• Combined Insurance Payment is displayed as currency.
• Unresolved Allowed Amount is displayed as currency.

Rounding rules

• Number displays use up to 2 decimal places in the calculator UI.
• Currency outputs are displayed with standard US dollar formatting.
• Input precision follows configured step values where provided.

Version history

Change log