Record a part payment or an advance

A customer paid half

Record exactly what arrived. Half a bill, a third of it, a round figure that does not match anything — all of it is recorded the same way, against the invoice it belongs to.

They paid part of it

Enter what they actually gave you. If it is less than the invoice total, the invoice shows as partially paid and the rest stays in what they owe you. No workaround, no rounding it off, no separate note to yourself.

They paid before the invoice

Record the payment anyway, without allocating it. It is held as an advance against that customer.

The next time you raise an invoice for them, the advance is offered against it automatically — so money taken in March does not get forgotten in April.

Checking what is sitting unallocated

Open the customer. Their page shows every invoice, every payment and the running balance, including anything paid but not yet applied to a bill.