What does a part-payment across two utility accounts look like in practice?

A regional water utility receives bank line `PAY-5521` for 412.60 from a landlord. The remittance note reads 'both units'. The landlord holds two accounts, `ACC-1180` and `ACC-1184`, with open invoices `INV-30417` (268.10, older) and `INV-30422` (190.75). Together they total 458.85, so the payment is 46.25 short.

The billing analyst opens the case from the unapplied-cash queue. Policy `POL-ALLOC-07` says that when a reference names several accounts, funds clear invoices in due-date order across them, and any shortfall stays on the newest invoice. The analyst applies 268.10 to `INV-30417` and 144.50 to `INV-30422`, leaving 46.25 open.

**State changes:** `PAY-5521` moves from unapplied to applied, `INV-30417` closes, `INV-30422` becomes part-paid, and the reminder on `ACC-1184` is rescheduled for the smaller balance. Had the full amount been posted to `ACC-1180` alone, that account would have shown a credit while `ACC-1184` moved to a late-fee stage.

**What it teaches:** one payment changes several linked records, and the right answer depends on a written policy, not on amount matching. A reseller can use this shape to explain to buyers why relational consistency and policy links are the first things to inspect.