Pricing and quoting, 29 October 2026
Spotting supplier price rises on invoices before they eat your margin
To spot supplier price rises, compare every line on every supplier invoice with the unit price you used in the quote or your price list, and flag anything that has moved by more than a set amount, such as 3%. Do it when the invoice arrives, not at year end. On a fixed-price job, every pound of rise you miss comes straight off your profit.
How much are material prices rising?
The government's all-work construction materials price index rose 6.0% in the 12 months to June 2026. Some items moved much more: fabricated structural steel rose 17.7%, rigid pipes and fittings 12.0%, and gravel, sand and aggregates 11.4%. Cement fell 4.5%.
Source: GOV.UK: Building materials and components statistics, July 2026 commentary
These are national averages. Your merchant's prices, your account discounts and the brands you buy will differ, which is why you check your own invoices and not an index.
What does a missed price rise cost you?
On a fixed-price job, the whole rise. Here is a £10,000 job, quoted at a 20% margin, where the materials were priced from last quarter's list and three lines then moved by the index amounts.
A £10,000 job where materials move after the quote
A plumbing and heating job, fixed price, materials costed at £3,000 when quoted.
| Price to the customer, excluding VAT | £10,000.00 |
| Cost as quoted: labour, materials, overheads£4,500 + £3,000 + £500 | £8,000.00 |
| Profit as quoted20% margin | £2,000.00 |
| Pipes and fittings, £1,000 at quote£1,000 × 12.0% | +£120.00 |
| Steel lintels and brackets, £800 at quote£800 × 17.7% | +£141.60 |
| Cement and aggregates, £200 at quote£200 × −4.5% | −£9.00 |
| Other materials, £1,000no change | £0.00 |
| Extra material cost | £252.60 |
| Profit after the rises£2,000 − £252.60 | £1,747.40 |
That's one job. Scale it up: a firm turning over £400,000 a year with a third of it in materials buys about £133,000 of materials. A 6% rise it never notices is about £8,000 off the year's profit, and the first sign is a bank balance lower than expected.
How do you check an invoice for price rises?
Match each line to your price list, compare unit prices, and act on anything over your tolerance. It takes a few minutes per invoice if your price list is in order.
- Keep a price list.
One sheet with each item you buy often, your supplier, the unit price and the date. Build it from recent invoices, not the merchant's list price, so it reflects your account discount.
- Set a tolerance.
Decide what counts as a rise worth acting on: 3% is a sensible start. Below that, update the list and move on.
- Check the invoice when it arrives.
Compare unit prices line by line, not the total. A total can look right while one item has jumped and another has dropped.
- Check quantities against the order and the delivery note.
Over-deliveries and duplicated lines cost as much as price rises.
- Query anything odd with the supplier the same day.
A changed discount or a missing account price is often a mistake you can get credited.
- Update the price list.
The next quote then uses today's price, which is the point of the whole exercise.
A groundworks firm buying £300,000 to £400,000 of materials a year told us it cut material costs by about 30% by switching suppliers once it could see what it was paying. It started by looking at unit prices invoice by invoice.
Can you pass a supplier price rise on to the customer?
Usually not on an accepted fixed-price quote. Citizens Advice tells consumers that higher costs for the trader don't justify a higher charge on a quote. You can recover a rise if your contract says so, or on work that was an estimate, but only to a reasonable price.
Give notice the way the clause says, with the supplier invoices as evidence. Get a solicitor to check the clause if the sums are large.
Tell the customer before you go over the estimate, explain why, and agree it in writing. Rising material costs are one of the things Citizens Advice says can make a higher bill reasonable.
The quoted price stands. Update your price list today and shorten the validity on future quotes.
The protection is upstream. Give quotes a validity date, say prices will be rechecked after it, and for long jobs consider naming the volatile items (steel, copper, timber) as provisional sums. The quote template shows where those lines go.
How often should you update your price list?
Every time an invoice shows a change over your tolerance, which in practice means weekly for an active firm. A price list updated once a year is wrong for most of the year. Getting material prices from builders' merchants covers how to ask for account pricing, and material markup covers what to add on top.
Where Nexley fits
Nexley is the AI back office for UK trade firms: five AI assistants run your tenders, quotes, buying, scheduling and invoicing. It connects to the tools you already work in, you run it all from WhatsApp, and you approve everything. £799 a month.
For supplier invoices, Nexley reads each bill as it arrives by email, matches it to the job, files it and checks every line against your price list. When a price has moved past your tolerance, it tells you on WhatsApp and updates the rate your next quote uses, once you approve.
Common questions
How much should I allow for price rises in a quote?
Use today's prices, keep the validity period short, and name volatile items as provisional sums on long jobs. Adding a blanket percentage for future rises makes you dearer on every quote, including those where prices don't move.
Should I check every invoice or only the big ones?
Every one, by line. Small invoices for fittings and consumables are where account discounts quietly drop off, and they add up across a year.
What tolerance should I use?
Start at 3% and adjust. Too low and you'll be checking rounding; too high and you'll miss steady rises on your biggest lines.
Can my accounting software do this?
Most accounting software records the bill but doesn't compare unit prices with your last purchase. You need a price list, a spreadsheet or a tool that does the comparison for you.
Sources
- GOV.UK: Building materials and components statistics, July 2026 commentary
- Citizens Advice: Problems with the cost of building work
- GOV.UK: VAT rates
Every rule, rate and date above was checked against these sources on the date shown at the top.
Topic: Pricing and quoting
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