There is a question where the answer is ‘cancelling the invoice once paid’. I don’t understand what cancelling the invoice means. Surely the payment is allocated to the invoice and this prevents the invoice being paid twice?
No it doesn’t because there is a risk that the same physical invoice goes through the system again. It can be easy in personal life to remember which bills have been paid unless you mark them ‘Paid’. Imagine what it’s like in a large business dealing with 100s of invoices per day.