AI Deep Dives

Supplier price creep: how to catch it in your invoices

By Steve McLean · 26 October 2026 · 6 minute read

Most price rises don't arrive with a letter. A few pence go on the lamb, the cream comes in a smaller tub at the same price, a delivery charge appears that wasn't there in spring. Each one is too small to notice on a busy Tuesday. Added up over a year, across every supplier, they can be thousands of pounds you never agreed to.

Why it's hard to see

Invoice totals go up and down anyway. You buy more in a busy week and less in a quiet one, so a bigger bill looks normal. The rise only shows when you compare the price of the same item, in the same unit, over time. Very few people have time to do that line by line, so most rises are simply paid.

It also helps to know what "normal" looks like right now. Two useful yardsticks:

A supplier's costs aren't the same as the national average, so a rise above these figures isn't proof of anything. But a line going up 10% or more when the index is under 3% is worth a polite question.

What price creep looks like

How to check your invoices in an afternoon

1. Pick your biggest suppliers. Three to five usually make up most of your spend. Start there.
2. Pick the lines that matter. The 10 to 20 items you buy most, by value. Ignore the rest for now.
3. Find the starting price. Your agreed price list, your contract, or the first invoice of the year.
4. Compare price per unit. Per kg, per litre, per item. Put old and new side by side in a simple table.
5. Work out the rise in pounds a year. A 5% rise on something you buy daily matters more than 20% on something you buy twice a year.
6. Look for doubles. Same supplier, same amount, within a week or two. Watch for invoice numbers that differ only by a prefix or a dash.

The sum

Extra cost per year = (new price − old price) × how many you buy a week × 52.

These are example numbers to show the sum, not an average or a real business. Your own invoices will give you the real figure.

Four ordinary lines, none of them dramatic, and the extra is over £3,600 a year. Most kitchens buy far more than four lines.

Don't forget the doubles

Paying the same invoice twice sounds rare, but it's easy to do when invoices arrive by email, by post and on a monthly statement. APQC's benchmarking puts the median at 1.5% of total yearly payments going out as duplicate or wrong payments, as cited by the payments firm Corpay. Common causes are the same invoice arriving through two routes, one supplier set up twice under slightly different names, and an invoice number re-typed with a different prefix.

What to say to the supplier

Keep it short, factual and friendly. Most suppliers will talk if you show them the numbers.

• "Lamb shoulder was £14.80 a kg on our January invoice and £16.90 on invoice 4471. We didn't get notice of the change. Can you explain it, or put it back to the agreed price?"
• "Invoice 4471 and 4478 look like the same delivery. Could you check and credit one if so?"

If a rise is fair, you've lost nothing by asking. If it isn't, you've got the money back, and the supplier knows you check.

Doing it without the spreadsheet

The afternoon method works, but it has to be repeated every month, and it usually isn't. Coral, Lagoona's finance team member, does the reading for you. You upload your supplier invoices, contracts and reports (PDF, Word or CSV), and it flags price rises, possible double charges and contracts about to renew. Every finding links to the page it came from, so you can check it yourself before you call anyone.

Coral flags and explains; it isn't an accountant or a lawyer. You decide what to raise with a supplier. Only your own managers and execs can open it, not your staff and not your IT provider. Its dashboard, Money found, shows what it found in pounds, each with its proof. It's for businesses of any size, from one site to a group; it pays off fastest for those spending around £15,000 a month or more with suppliers. Coral is £649 a month, running costs included, with no contract.