A missing purchase order, delivery confirmation, contract term, or vendor identity check leaves the invoice unverified. Record exactly what is absent and who can provide it. Continue checking the parts you can—amounts, dates, and duplicate numbers—but do not mark the invoice approved solely because its arithmetic works.
If payment is due soon, escalate the missing document to an authorized decision-maker. Verify unfamiliar invoices and changes to bank details using a contact method already on file, not details supplied in the invoice itself. Keep the case pending until the evidence or an approved exception is recorded. The goal is to avoid both unnecessary delay and an unsupported payment.