...
A while back, when working in a customer's restaurant on his laptop,
I spilled a drink across the keyboard. My insurance company paid
promptly, and sent a cheque directly to the customer who replaced the
machine.
I have a £100 excess on my insurance, however, and would like to set
this against invoices (long) owed by the customer.
Cash->Receipt
As long as there's an open invoice for the customer, you can apply any
payment amount to that invoice. If it's less than an invoice, put the
amount paid in the invoice line, and update -- the total should update
appropriately. If it's an overpayment, check the invoices and update,
and then put the total received in total box, and post. LSMB will put
the extra payment in an AR transaction with a negative amount.
The next time you go to Cash -> Receipt, you'll see this
overpayment and
can apply it to a new invoice.
At least, that's how we do it here.