FA-68823 / Toll and parking fee computation / Member archive

Parking tax and fee composition: tax is computed on the undiscounted price · case 03

Parking tax and fee composition returns a wrong result when tax is computed on the undiscounted price.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input {base, resident, resident_pct, tax_bp (basis points), surcharge, app, app_fee}. Residents get resident_pct off (discount floored). Parking tax on the discounted base is rounded half up per transaction. The surcharge is untaxed. App payments add app_fee plus its own tax rounded half up. Return {base, tax, total}.

Why this case matters

Fee engines bill customers in integer cents; a wrong boundary, rounding stage or cap scope silently over- or under-charges.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
fee oracle 1	`{"base": 2066, "tax": 930, "total": 3146}`	`{"base": 2066, "tax": 465, "total": 2681}`	Failed

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