FA-57952 / Double-entry ledger accounting / Member archive

Bank reconciliation: nsf check direction · case 02

A bounced customer check increases the adjusted cash balance.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

x = {'bank': statement balance, 'book': ledger cash balance, 'items': [[kind, ...]]}. Bank side: deposit_in_transit adds, outstanding_check subtracts, bank_error adds its signed correction. Book side (each produces an adjusting entry [kind, signed amount] in input order): bank_fee and nsf subtract, interest adds, collection [kind, face, fee] adds face - fee, check_error [kind, recorded, actual] adds recorded - actual. Other kinds are ignored. Return {'adjusted_bank', 'adjusted_book', 'reconciled', 'entries'}.

Why this case matters

Ledger software must keep debits equal to credits and apply normal-balance, period and cutoff rules exactly; small sign or boundary slips silently misstate financial statements.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: nsf check direction	`{"adjusted_bank": 12410, "adjusted_book": 9310, "entries": [["nsf", 400], ["bank_fee", -90]], "reconciled": false}`	`{"adjusted_bank": 12410, "adjusted_book": 8510, "entries": [["nsf", -400], ["bank_fee", -90]], "reconciled": false}`	Failed

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