Invoice capture is evaluated on extraction accuracy and should first be evaluated on completeness. An invoice that never reaches the system is not read badly, it is not read at all, and it surfaces weeks later as a supplier telephoning about a payment. Getting every invoice into one queue is the first job, and it is usually a process change rather than a purchase.
Count how invoices actually arrive
Take a month and classify every invoice by how it reached you: shared mailbox, post, supplier portal, photograph from a site, or an individual's inbox. The last category is nearly always larger than expected and is entirely invisible to a capture product, because those invoices never pass through the channels it monitors.
Consolidate before you automate
Tell suppliers one address, redirect what arrives elsewhere, and schedule the portals as a named task. This is a quarter of polite persistence and it permanently removes a class of surprise. Automating capture on top of four uncontrolled channels produces a system that is accurate about the invoices it sees and silent about the rest.
Then measure accuracy where it matters
Once everything lands in one queue, extraction quality is worth comparing, on your own worst documents and by field. Header fields will be fine. Lines and anything inferred will not. Design the review around the second group and leave the first alone, which is where the time saving actually comes from.
Questions people ask about invoice capture
How do we know if invoices are being missed?
Supplier statements are the reliable check: reconciling one shows invoices the supplier raised that you never recorded. Doing this for your largest suppliers finds leaks quickly.
Can capture handle credit notes and statements?
It should classify them separately rather than treating everything as an invoice. Misclassification is more expensive than misreading.
Is it worth capturing invoices we key anyway?
Yes, for the record and the received date, even before any keying saving. Knowing when a document arrived answers most payment-term disputes.