How to check an invoice for errors before paying

Start with whether the invoice is the right document

Confirm the supplier or vendor name, your legal name as the bill-to party, the invoice number, and the invoice date. A correct total on the wrong entity, or a duplicate invoice number, is still a problem. If the document is a pro-forma, statement, or delivery note labelled as an invoice, pause before treating it as payable.

Rebuild the line items, not just the footer

For each line, check description, quantity, unit price, and line total. Then multiply quantity × unit price yourself. Invoice errors often hide in a line that looks familiar while the quantity or unit price has moved. If you have a quote, purchase order, or work report, compare those fields next — that is two-way invoice matching.

Watch for extra lines that were never agreed, missing lines you expected, and units that changed (hours vs days, boxes vs pieces).

Check tax after the taxable base is right

VAT or sales tax is only meaningful after the net amounts are correct. A tax figure can be internally consistent and still be wrong if it follows an inflated subtotal. Check the stated rate against the jurisdiction and the type of supply, then check that tax amount = taxable base × rate, within normal rounding.

Recompute subtotal and total

Add the line nets, add tax, subtract any stated discount or withholding, and compare with the invoice total. If the footer is round and the lines are not, find which line was adjusted. If you only glance at the total, you will miss invoice overcharges that were padded into a single line.

Dates, terms, and references

Compare due date and payment terms with the quote or purchase order. Check any PO number, job number, or period of work. A bill can be arithmetically perfect and still be for the wrong period or the wrong order.

When an automated check helps

If both documents are in front of you as PDFs or photos, an invoice checker can surface the same class of differences — price, quantity, tax, dates, and totals — so you spend time on exceptions. Payment Check does that as a two-document review. It does not store files in a database and it does not approve payment.

For more on purchase-order comparison, see invoice vs purchase order. For patterns people skip, see common invoice errors. If your process also requires a goods receipt, read how three-way matching works.