FA-62409 / Tax bracket computation / Member archive

Indexed thresholds are rounded to the nearest 50 instead of down · case 04

Some thresholds are 50 higher than the published figure.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

solve(base, factors): base is a list of statutory thresholds; factors are yearly inflation factors (decimal strings). For every year, a threshold is the base times the cumulative product of factors so far, rounded DOWN to a multiple of 50 (indexing always starts again from the unrounded base, never from a previously rounded value). A threshold may never fall below its previous year's value. Return the final-year thresholds.

Why this case matters

Tax computations hinge on which slice, threshold, ordering and rounding rule applies at each step; a misplaced boundary silently misstates liabilities.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression rounding-direction 1	`[10400, 104500, 12050]`	`[10350, 104500, 12050]`	Failed

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