FA-62959 / Insurance premium rating / Member archive

Increased limits factor layer pricing: Excess layer subtracts the wrong lower factor · case 04

Excess layers are charged the full ground-up premium.

Member previewVariant 4 · 3 implementations · 10 checks per implementation

Case contract

Input basic (premium at basic limit), ilf table [[limit, factor*1000]] ascending, attachment, layer_limit. ILF(0)=0 and ILF is linear between tabulated points (including from 0 to the basic limit); limits above the table are unrated. Layer premium = floor(basic*(ILF(att+lim)-ILF(att))/1000+1/2). layer_limit<=0 or attachment<0 -> 'invalid'.

Why this case matters

Premium rating engines apply ordered tabular rules where one misplaced boundary or step silently misprices policies.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
excess layer 500 xs 500	`189801`	`26788`	Failed

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