Invoice errors
Common invoice errors businesses miss
Most invoice discrepancies are not dramatic. They sit in a familiar line, a tidy total, or a tax figure that follows a wrong net. Use this list with the invoice and the quote or purchase order side by side — then decide what to query before you pay.
Incorrect quantity
The billed quantity is not the quantity ordered or delivered. It happens when a template is reused, a partial shipment is billed in full, or the unit of measure changes (boxes versus pieces, hours versus days). Rebuild quantity × unit price on every material line. If you have a receipt, also compare billed quantity with received quantity — that is the extra step in three-way matching. Hold payment on the excess until the supplier revises the invoice or you accept a change.
Incorrect unit price
The description looks right; the rate does not. Repeat suppliers and contractor templates do this often. Compare the unit price to the purchase order or quote, not to last month’s memory. Before paying, ask whether a change order exists. If it does not, ask for a credit or a corrected invoice.
Incorrect subtotal
Line nets do not add to the stated subtotal. Someone rounded aggressively, dropped a line, or adjusted the footer to a round number. Add the lines yourself. If the subtotal is wrong, tax and total that follow it are derived errors — fix the net first.
Incorrect tax or VAT
A tax amount can be internally consistent and still be wrong if it follows an inflated net, uses the wrong rate, or applies tax to a line that should be out of scope. Check the stated rate against the type of supply in your jurisdiction, then check that tax ≈ taxable base × rate, within normal rounding. Do not treat a tax mismatch as independent until the lines are correct.
Incorrect invoice total
Subtotal, plus tax, minus any stated discount or withholding, should explain the total. If they do not, find the silent adjustment. A plausible footer is how overcharges get paid: one padded line, a clean total. Recalculate before you release funds.
Duplicate charges
The same work appears twice: two invoices with one number, a resubmitted PDF, or the same line billed on a progress invoice and again on a final bill. Search recent payments for the supplier, amount, and invoice number. Do not pay a second time because the file looks new.
Incorrect invoice date or service period
The date or period does not match the PO, the work report, or the month you thought you were closing. That changes cut-off, late-fee risk, and what you are actually buying. Confirm the period before treating the invoice as this cycle’s payable.
Wrong purchase-order number
The invoice cites no PO, the wrong PO, or a closed order. Matching then fails even if the maths is perfect. Ask the supplier to reissue with the correct reference, or attach the authorizing quote if you never raised a PO. Invoice and purchase-order fields that should agree are listed separately.
Mismatched supplier information
Legal name, address, tax identifier, or bank details do not match the vendor you contracted. That can be a simple entity change or a payment-redirection attempt. Stop and confirm with a known contact before you change master data or pay.
Unexpected fees
Sundry, rush, travel, fuel, or “administration” lines that were not on the quote. They are easy to miss because the main item looks right. Highlight any line that has no counterpart on the supporting document and ask whether it was agreed.
Discount discrepancies
An agreed discount or early-payment term is missing, or a discount is taken that you did not offer. Check the PO or contract for the rate and the window. Paying the gross without the discount is a quiet overpay.
Currency discrepancies
The invoice currency is not the PO currency, or a conversion was applied without an agreed rate. Confirm the currency code on both documents. If conversion is expected, confirm the rate and who bears the difference before you pay.
Payment-term discrepancies
Due on receipt instead of net 30, or a due date that does not follow the stated terms. That changes cash timing, not the arithmetic. Compare terms with the quote or PO and dispute the due date if the contract is different.
How to use this list
Work through the invoice and the supporting document together. A step-by-step invoice review gives the order: identity, lines, tax, totals. An online comparison against a quote or PO can surface the same class of differences so you spend time on exceptions. Results are for review, not payment approval.