Invoice management processes are usually well developed in the middle, around matching and approval, and weak at both ends. Arrival, because invoices come in through channels nobody controls. Closure, because nothing forces an invoice to be explicitly finished. Both weaknesses produce the same symptom, which is a queue that nobody quite trusts.
Arrival: one door, one date
Every invoice should enter through a channel you monitor, and the date it entered should be recorded. Invoices sent to individuals are invisible until somebody forwards them, and by then the payment terms have been running. Consolidating channels is a quarter of polite persistence with suppliers and colleagues, and it permanently closes the biggest leak.
The middle: match, exception, approve
Compare against the order and the receipt, route what fails by its reason, approve by the written rule, code and schedule. This part is usually the best understood, and it is where software helps most. It is also, for that reason, rarely where the remaining problem is once the ends are fixed.
Closure: explicit rather than implied
An invoice should end in a definite state: paid, credited, cancelled or written off with a reason. Invoices that simply stop being discussed accumulate in the open list, and after a while the list is not trusted, at which point it stops being used and everybody goes back to asking each other. Explicit closure keeps the record credible.
Questions people ask about invoice management process
How do we handle invoices we will never pay?
Close them explicitly with a reason, having told the supplier. An unpaid invoice left open indefinitely is a dispute nobody is managing.
What date should the record carry?
Both: the invoice date from the document and the date it reached your organisation. Terms usually run from the latter and disputes usually turn on it.
How do we stop the open list going stale?
Age it and review the oldest items weekly. A list nobody reviews stops being accurate very quickly, because nobody notices when it is wrong.