FA-59155 / Payroll withholding rules / Member archive

Aggregate-method supplemental withholding: credit for actual withholding · case 05

Employees with W-4 extra withholding on regular pay are under-withheld on bonuses paid with that run.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input {regular, supp, regular_wh or None, table: ascending [[threshold, base, pct]]}. f(w) uses the last row with threshold <= w: base + (w - threshold)*pct/100 half-up. Supplemental withholding = max(0, f(regular + supp) - already), where already is regular_wh when given, otherwise f(regular) (supplemental paid separately from the regular run). Return cents.

Why this case matters

The aggregate method withholds on combined wages, then credits what the regular payroll already withheld.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression 0	`60852`	`40272`	Failed

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