FA-58883 / Payroll withholding rules / Member archive

Additional Medicare withholding threshold: additional rate unit · case 03

Additional Medicare withholding is ten times too large once the threshold is crossed.

Member previewVariant 3 · 3 implementations · 10 checks per implementation

Case contract

Input [ytd_wages, wages] in cents. Regular Medicare is 1.45% of wages rounded half-up. Additional Medicare is 0.9% of the part of this paycheck that pushes year-to-date wages above 200,000.00, rounded half-up separately. Return [medicare, additional_wages, medicare + additional].

Why this case matters

The employer must begin the extra 0.9% exactly with the paycheck that crosses the threshold, and only on the excess portion.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression (boundary) 0	`[179, 12345, 1290]`	`[179, 12345, 290]`	Failed

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