A quote with no date on it is an open offer. Your customer can sit on February’s price until May, accept it, and you are bound - materials drift and all. The fix costs one line: say how long the quote is valid (30 days is common trade practice, not a legal rule), and re-confirm materials prices before booking anything older. With building materials up 3.2% in the year to April 2026 (Department for Business and Trade), that line is doing more work than it used to.
Until the customer says yes, the price is yours to control
The mechanics are worth knowing precisely. A quote is an offer, which the customer may accept or reject - that is how Business Companion, the government-backed trading standards guidance, describes it. The moment they accept, it becomes a binding agreement, “whether it’s written down or not”, as Citizens Advice tells your customers. And under the Consumer Rights Act 2015, what you say or write to a consumer - a quotation included - is binding where they rely on it in deciding to buy.
From then on you cannot charge more than the quoted figure unless the customer asks for extra work, you flag extra work and they agree to pay for it, or a genuine mistake was made writing down or calculating the price. “Steel went up since February” appears nowhere on that list.
So the only moment you control is before acceptance. An undated quote is an offer that sits open, at a price fixed on the day you wrote it. A dated quote expires on your terms - and the date has to be there before the customer says yes.
What materials actually did in the year to April 2026
The DBT’s all-work materials index rose 3.2% in the year to April 2026, and 1.1% in April alone - a single month worth around a third of the whole year’s move. The drift is real, and it is not smooth.
It is not uniform either. Fabricated structural steel rose 8.5% over the year; gravel, sand and clays (including the aggregates levy) 7.7%; aqueous paint 6.1%. Meanwhile concrete reinforcing bars fell 5.2%, cement 4.5%, and precast blocks, bricks and tiles 3.2%. Two things follow. Your exposure depends on the mix of the job, not the headline rate. And because prices move both ways, a dated quote protects the customer from locking in a stale high price just as it protects you from honouring a stale low one. It is fair dealing, not margin-grabbing.
What a three-month-old quote costs
Take a garage conversion shell quoted in early February 2026 at £14,500, with £6,000 of materials and a planned net profit of £1,100. The job figures are illustrative; the inflation rates are the DBT’s. The customer comes back in early May and accepts. You are now buying May’s materials at February’s price.
Weight the basket by what is actually in it, pro-rating each annual rate across the three months the quote sat open (a linear simplification, but a reasonable one):
- £2,000 of structural steel at 8.5% a year ≈ 2.1% over the quarter: about £42
- £1,500 of aggregates at 7.7% a year ≈ 1.9%: about £29
- £2,500 of general materials at the 3.2% headline ≈ 0.8%: about £20
Call it £91 you cannot recover. If the spring pace had continued instead - three months at April’s 1.1% is roughly 3.3% - the same £6,000 drifts by about £200.
Against the planned £1,100 profit, that is roughly 8–18% of the job’s profit gone before a tool comes off the van. Not because the number was built wrong - if you’ve priced the job from the ground up, the build-up was sound - but because the price had no expiry date.
Set a window, and say it in writing
There is no statutory validity period. No law says 30 days; it is simply common trade practice. But your customer is already being told to expect one: Citizens Advice’s guidance on getting building work done says a written quote should include “how long the price is valid for”. Stating a window is not sharp practice - it is what the customer’s own advice service says a proper quote looks like. The same guidance tells consumers to treat a trader who won’t put a quote in writing as a red flag, so a dated, written quote also reads as professionalism.
One line does it. This is our suggested wording, not from any official source:
This quote is valid for 30 days from the date above. If you accept after that date, we will re-confirm materials prices before the work is booked and agree any change with you in writing.
What not to do: bury a clause that silently passes materials increases through after acceptance. The trading standards guidance is clear that changes to a contract should be agreed by both parties and recorded in writing, because disputes grow out of misunderstandings about what was agreed. The clean pattern is a dated window before acceptance and an agreed, written variation after - never a price that quietly moves on its own.
Re-quoting without losing the job
When a stale quote comes back to life, re-confirm rather than renegotiate. Check live prices on the lines that matter, adjust only those, and send it back the same day with one sentence of explanation: “Steel and aggregates have moved since February, so materials are now £6,091 and the job is £14,591. I’ll hold that price for 30 days.” Specific, dated, done. The habits that win quotes in the first place - speed and a clear breakdown - are exactly what makes a re-quote land.
And honour the downside. If the job is heavy on cement or reinforcing bar, both cheaper than a year earlier, say so and re-quote down. Nothing builds trust faster than a trade volunteering a lower number, and it turns the validity window into what it should be: a fairness device that protects whichever side the market moved against.
The takeaway
Date every quote. Thirty days is the common window; put it in writing on the quote itself, re-confirm materials prices on anything older before you book the work, and record any agreed change in writing. One sentence on the page turns materials drift from something you silently absorb into something you openly reprice.
