Check invoice quantity and unit price without treating totals as proof

Where the extra work starts

Check the relationship between the fields so the workbook is useful for line-item work, not just a plausible total.

Upload a representative supplier invoice, inspect its extracted fields and line items beside the PDF, then download Excel. Put the awkward invoice in your trial too: the useful result is less total work after corrections.

The arithmetic check is a consistency aid, not invoice approval. Discounts, base quantities, charges and rounding can make a simple quantity-times-price assumption inappropriate.

A practical way to get it right

Record the raw quantity, price, amount and any visible unit or price basis. Follow the source reference for each field and confirm its column and row. Keep the original strings before converting values for a calculation, including decimal places and signs.

Only after field verification, determine whether a simple multiplication is supported by the document. If the price applies per pack or per multiple units, preserve that basis and ask the reviewer how the comparison should be performed. Do not change a source value merely to make the arithmetic agree.

Record the arithmetic result in a separate check column with its assumptions. A mismatch becomes a review question: extraction error, source inconsistency, omitted adjustment or an incorrect calculation model. These possibilities require different responses.

OpenPeppol: Invoice line price details distinguishes price from price base quantity. Inspect that basis before assuming every printed price is for one invoiced unit.

What this looks like on a real task

Synthetic example. The people, references and figures below are invented to demonstrate the method.

Both pairs multiply to 48.00, so checking only the amount misses two incorrect fields. Copy the version, field values and finding columns into a review note. The example deliberately uses simple unit pricing; do not apply its arithmetic to a document with a different stated price basis or adjustment structure.

Catch the cases that create rework

A displayed amount may be rounded while the underlying calculation uses more precision. Preserve the source and ask the authorized reviewer to assess the difference rather than inventing a tolerance. A blank quantity or price should remain unresolved, not be reverse-calculated from the total and presented as extracted evidence.

Do not let a formula overwrite raw cells. Keep calculations in distinct columns so another person can distinguish transcription from interpretation.

OpenPeppol: Invoice line syntax models quantity and line amount as separate fields. Review both directly; a correct-looking amount does not validate the other extracted fields.

Decide whether the change is worth keeping

A completed check should show exact source matches for quantity, price and amount, plus the result of any supported arithmetic comparison. Record unresolved assumptions explicitly. If the workflow repeatedly spends effort reconstructing price bases, that is a separate review problem from extracting columns and should be measured separately before considering automation.