FA-63170 / Insurance premium rating / Member archive

Calendar period earned and unearned premium: Overlap ignores the period start · case 05

Policies written before the period are credited with earnings from before it began.

Member previewVariant 5 · 3 implementations · 11 checks per implementation

Case contract

Input period [start, end) in days and policies [[written day, term days (>0 else 'invalid term'), premium]]. Earned = premium*overlap/term where overlap = max(0, min(end, w+term) - max(start, w)). Unearned at end counts policies written before end and still in force after it. Sum exactly; round each total half-up once.

Why this case matters

Earned premium is the denominator of every loss ratio, so exposure-overlap slips distort rate indications.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
written before period	`[162636, 0]`	`[97582, 0]`	Failed

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