Best practice in invoice approval is unglamorous and specific. Most of the elapsed time in payables is an invoice waiting on somebody who is travelling, in meetings or on leave, so the practices that matter are the ones that address absence and ambiguity rather than the ones that make the approval screen prettier.
Route to a person, first time
By cost centre and value, to a named individual rather than a group. Group queues produce items everybody can see and nobody progresses, and the effect is worst on the exceptions where the work actually is. Where a group is genuinely correct, assign one owner anyway and allow reassignment.
Cover absence without being asked
Delegation triggered by declared leave, plus a fallback after a fixed period of inactivity regardless. Manual delegation is forgotten exactly when it is needed, because unplanned absence is unplanned, and this single setting removes most of the long tail that suppliers notice and remember.
Escalate rather than remind
A reminder repeating into the same silent inbox produces more silence. Escalation to a named alternative after a defined period makes elapsed time predictable enough to promise a supplier a date, and the period should be chosen by working backwards from your payment terms rather than left at a default.
Show the approver the invoice
The document, the amount, the supplier, what it is for and the match result. An approver shown a reference and a total is confirming that a number exists rather than authorising an expenditure, and they know it. This is the difference between a control and a formality, and it costs nothing to get right.
Questions people ask about invoice approval best practices
How many approvers should an invoice need?
As few as your delegated authority allows. Each level adds elapsed time and dilutes responsibility, and two approvers each assuming the other checked is a documented failure.
Should matched invoices need approval?
Where a clean match within tolerance is treated as authorisation, no. Write it down as a policy rather than letting it be a configuration default.
What should we measure?
Elapsed time from receipt to approval as a distribution rather than an average. The tail is where the complaints and the cost are.