Draw an invoice approval workflow and it looks fast: arrive, match, route, approve, pay. Measure one and it takes days, and almost all of that is waiting rather than working. The workflow that performs well is not the one with the cleverest rules but the one designed around the two situations that generate the waiting, which are absence and ambiguity about who owns something.
Absence: cover before it is needed
Approvers take leave, travel and change roles. A workflow that stops when one of them does is a workflow that stops regularly. Declared-absence delegation handles the planned case; time-based escalation to a named alternative handles the unplanned one. Between them they remove the long tail, and the long tail is where the cost is.
Ambiguity: a default owner for everything
Some invoices will not route: a new cost centre, an unfamiliar supplier, a category nobody configured. These must land with a named person rather than in an unowned queue. An invoice that routes nowhere is the one discovered weeks later, and a default owner costs nothing while a lost invoice costs a supplier relationship.
Instrument the wait, not the work
Measure elapsed time from receipt to approval and look at the distribution, not the average. The tail will point at specific approvers, specific cost centres or specific document types, and each of those is a fixable, concrete problem. Averages hide exactly the cases you need to see.
Questions people ask about invoice approval workflow
How many approval levels should there be?
As few as your delegated authority allows. Each level adds elapsed time and dilutes ownership, and two approvers each assuming the other checked is a recognised failure mode.
Should matched invoices still be approved?
Many organisations treat a clean match within tolerance as sufficient, because approval already happened at the order. Decide it explicitly rather than by default.
How do we handle disputed invoices?
Give them their own status with an owner and an age, so they are visibly parked rather than silently stuck. A dispute that ages invisibly becomes a supplier problem later.