The checklist
| # | Discrepancy | What it looks like | How to check |
|---|---|---|---|
| 1 | Line price ≠ contract price × quantity | Line total higher than the agreed price allows | Recalculate each line with the contract unit price |
| 2 | Document total ≠ sum of lines | Total, discount or tax does not add up | Re-add the lines; check discounts and tax separately |
| 3 | Date missing | No invoice or delivery date | Reject for correction; dates decide which price list applies |
| 4 | Non-positive quantity | Zero or negative quantity on a charge line | Credits belong on a credit note, not hidden in an invoice |
| 5 | Supplier tax ID mismatch | Tax ID differs from the supplier on file | Compare with your supplier master data |
| 6 | Wrong order or contract reference | Invoice points to another project’s contract | Compare with the contract of the project that received the goods |
| 7 | Steel weight outside tolerance | Invoiced tonnage well above the delivered weight | Compare with delivery weights; agree an acceptable tolerance |
| 8 | Unit price differs from the contract | Old price list, list price instead of agreed price | Compare with the contract version in force on the delivery date |
| 9 | Unit inconsistency | Invoiced per m² but contracted per unit, or t vs kg | Convert or query; never compare numbers in different units |
| 10 | Designation mismatch | D16 invoiced, D22 delivered; C30/37 invoiced, C25/30 delivered | Compare product identity, not just the description text |
Price discrepancies (checks 1 and 8)
These are the checks most people think of first. They fail for mundane reasons: the supplier’s system still has last year’s price, a different project’s price was applied, or the list price was used instead of the agreed one. The fix is the same: have the right contract version open, and compare unit price per item, not totals. For example (illustrative): 38 t of rebar at €905.00/t instead of the contracted €880.00/t is a €950.00 difference that no total-level check will reveal.
Arithmetic and data discrepancies (checks 2 to 5)
Totals that do not add up, missing dates, odd quantities and the wrong tax ID are rarer but quick to check, and they are also the ones that cause trouble downstream in accounting. A wrong supplier tax ID usually means the invoice belongs to a sister company or was keyed wrong, and it should be corrected by the supplier rather than by you.
Quantity, unit and product discrepancies (checks 7, 9 and 10)
These are where construction differs from other industries. Rebar is sold by weight while the site counts bars; the weight on a delivery (theoretical or weighed) and the invoiced weight can legitimately differ a little, so agree a tolerance and query anything beyond it. Tiles and panels move between units and m². And a designation that differs by one character — D16 vs D22, C25/30 vs C30/37 — is a different product at a different price. Always compare the delivered item on the delivery note with the invoiced item.
Reference, duplicate and missing-delivery discrepancies
- Wrong contract reference (check 6) — the invoice will be priced and costed on the wrong project. Check it before anything else.
- Duplicate invoice — the same invoice by email and on paper, or the same delivery on two invoices. Check invoice number per supplier; in Portugal, the ATCUD is a unique document key (ATCUD explained).
- No delivery behind the line — see invoice without a delivery note.
What to do when you find one
- 01Write down the exact difference: document, line, expected value, invoiced value, amount.
- 02Check it is not your error — the right contract version, the right project, all delivery notes found.
- 03Send it to the supplier with the references and ask for a credit note or a corrected invoice. In Portugal a credit note must reference the invoice it corrects (VAT Code, art. 36(6)).
- 04Approve the undisputed part where your process allows it, and track the disputed amount until the credit arrives.
Automating the checklist
The ten checks above are the ten deterministic validations (V1–V10) Audiree runs on every document after AI has read it line by line, with two independent readings, and matched each line by meaning to the contract price list of the project. Duplicates are detected by document number or ATCUD plus supplier. What passes is approved automatically; each discrepancy goes to a review queue with the exact difference, so the team spends its time on the documents that need a decision. For the full method, see how to reconcile supplier invoices.
Audiree is built in Portugal and works today with Portuguese construction companies. Reading is layout-agnostic, so documents from any supplier can be processed; if you work in another market, a demo with your own documents is the honest way to check the fit.
Frequently asked questions
What is the most common invoice discrepancy?
We have not measured a frequency we can publish. In practice, price differences against the contract and quantities that do not match delivery notes are the ones teams spend most time on.
What tolerance should we use?
That is a business decision and depends on the material. Weighed materials such as steel usually need a small tolerance; unit-priced items usually need none. Agree it with suppliers in the contract where possible.
Should we correct the invoice ourselves?
No. Ask the supplier for a corrected invoice or a credit note, so both sets of books agree.
Is a wrong tax ID a reason to reject an invoice?
It is a reason to ask the supplier to correct it before you book it. Confirm the treatment with your accountant.