FA-63528 / Actuarial life tables / Member archive

Deferred annuity with guaranteed period: Guarantee covers one payment too many · case 03

A 3-year certain period guarantees four payments.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input l (from issue age), defer n, guarantee g, term (None = to end of table), i. Payments at times n..end-1; the first g payments are certain once the annuitant survives the deferral (probability l_n/l_0), later payments need survival to k. PV = sum v^k * probability, rounded to 6. l_0=0 or negative n/g -> 'invalid'.

Why this case matters

Life-table arithmetic compounds across ages, so one misplaced index or assumption shifts every downstream value.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
deferred with guarantee	`5.368988`	`5.339789`	Failed

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