How to reconcile supplier invoices with delivery notes and contract prices

In accounts payable, a three-way match compares the invoice with the purchase order (what was agreed) and the receipt (what arrived). Construction bends this in one way: for recurring materials — concrete, rebar, aggregates, blocks, rental — prices are usually agreed once per project or period in a supply contract or price list, not in a purchase order for each delivery. So the three legs are:

• The delivery notes — signed on site; evidence of what and how much was delivered, and where. See what is a delivery note.
• The invoice — what the supplier charges, often one per month covering many deliveries.
• The contract price list — the agreed unit price per item and unit (m³, t, kg, day, unit), plus any agreed extras such as pumping or part-load surcharges.

• All delivery notes for the period and the supplier, sorted by project (site). Missing notes are the first thing to chase.
• The current contract or price list for that supplier and project — the version in force on the delivery dates.
• The invoice, and any credit notes already received.
• A register of what has already been invoiced, so you can spot a delivery billed twice.

1. 01Check the header. Supplier name and tax ID, your company’s details, invoice number and date, project or order reference. A wrong reference is how invoices end up on the wrong project.
2. 02Check for duplicates. Has this invoice number (in Portugal, also the ATCUD) been received before from this supplier?
3. 03List the delivery notes the invoice covers. If the invoice references them, tick them off; if not, take every note from that supplier and project in the period.
4. 04Sum delivered quantities per item. Group notes by product and unit — for example all C25/30 concrete, all 16 mm rebar — and add them up.
5. 05Compare quantities line by line. Invoiced quantity against delivered quantity for each item, in the same unit.
6. 06Compare unit prices with the contract. Each line’s unit price against the contract price for that item. Then check the arithmetic: unit price × quantity = line total.
7. 07Check extras. Pumping, waiting time, part loads, transport, pallets: is each one allowed by the contract and backed by a delivery or site record?
8. 08Check the totals. Sum of lines, tax, invoice total.
9. 09Record the result. Approve what matches; for everything else write down the exact difference and ask the supplier for a credit note or an explanation. A Portuguese credit note must reference the invoice it corrects.

A concrete supplier sends one invoice for a site’s May deliveries: €14,280.00 before VAT. The contract says €92.00/m³ for C25/30 and €180.00 per pumping service.

Differences are normal; losing track of them is the problem. Decide in advance which differences you accept (a tolerance — for example small weighbridge variations on steel) and which always go back to the supplier. For everything else, send the supplier the exact difference with the document references, and park the disputed amount rather than the whole invoice where your process allows it.

The most frequent causes — price differs from the contract, quantity not delivered, wrong unit, wrong product, duplicate invoice — are listed with checks in common supplier invoice discrepancies. Invoice lines with no delivery at all get their own procedure: invoice without a delivery note.

Not because any step is hard, but because the documents never meet. Delivery notes sit with the site; invoices go to the office; the price list lives in someone’s email. Notes get lost, wet or photographed badly. The description on the note ("C25/30 XC2 S3 Dmax 22") rarely matches the contract wording ("BET C25/30"), so every line needs a human to decide they are the same thing. And in many companies the same document is checked twice: the site confirms quantities, finance confirms prices, each in its own spreadsheet.

Automation only helps if it does the tedious part — reading every line and pairing it with the right contract item — and leaves judgement to people. That is how Audiree works. The site photographs each delivery note when it arrives, in the chat group it already uses; AI reads every line (article, quantity, unit, price), with two independent readings, and matches each line by meaning to the contract price list of that project. When the invoice arrives, ten deterministic validations run: line price against contract price, totals, date, positive quantities, supplier tax ID, contract reference, rebar tonnage tolerance, unit consistency and designation identity (for example D16 vs D22). What matches is approved automatically; divergences go to a review queue with the exact difference, and nothing is discarded silently. The per-project dashboard shows contracted against invoiced, and data exports to CSV for Excel.

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.