Top 5 quote mistakes UK tradespeople make (and what they cost you)

A mate of mine finished a loft conversion in March and came off it £2,600 down on what he thought he was making. Nothing went wrong on site. No disaster, no rework, no cowboy supplier. He'd written a one-line quote, the customer kept adding bits, he kept saying yes, and the price never moved because nobody ever wrote anything down.

That's the thing about quoting badly. It doesn't blow up. It leaks. You lose a couple of hundred here, a day's labour there, and at the end of the year you've worked flat out for less than you'd have made employed.

These are the five mistakes that do most of the damage, what each one costs in real money, and the fix for each. None of the fixes take more than ten minutes to set up.

Mistake 1: A price with no scope

The quote says "Bathroom refit, £5,400". That's it. One line, one number, off it goes.

The problem isn't the number. The problem is that "bathroom refit" means whatever the customer decides it means when they're standing in the room on week two. Does it include lifting and re-laying the floor? Boxing the pipework? Making good the plaster where the old cabinet came off? Taking the rubble away? Second-fixing the extractor? You know what you priced. They don't, and when there's nothing written down, the gap gets filled in their favour.

You then have two options, both bad. Do the extra work for nothing, or have the conversation about money halfway through a job while you're standing in their house. Most trades pick the first one because the second one is horrible.

The fix

Two lists on every quote. What's included, and what isn't. The exclusions list is the one that earns its keep.

The corroded pipework line alone has saved me more arguments than everything else on the page. You can't see behind a boxed-in soil stack until the suite is out, and if you haven't excluded it, the customer reasonably thinks it's your problem.

Mistake 2: Guessing the day rate instead of working it out

This is the expensive one. Ask most self-employed trades where their day rate came from and the honest answer is that it's roughly what the lads in the area charge, maybe a bit under so they win more work.

That number has nothing to do with what you need to earn. Here's the maths done properly.

Worked example: Adam Wójcik trading as Wójcik Plumbing

Solo plumber, domestic work, no subbies. He wants to take home £45,000 before tax.

Step 1: annual overheads. Everything he pays for whether he works or not.

• Van finance and running costs: £4,800
• Public liability and tool insurance: £650
• Tool replacement and hire: £1,200
• Phone, job software, fuel card admin: £480
• Accountant: £600
• Gas Safe registration and CPD: £550
• Workwear, consumables, PPE: £500
• Total: £8,780

Step 2: what he needs to turn over on labour. £45,000 + £8,780 = £53,780.

Step 3: the billable days, honestly counted. There are 52 weeks. Take off 4 weeks holiday, a week of illness and family stuff, and a week of dead time between jobs. That's 46 working weeks. Out of each week, roughly one day goes on quoting, buying materials, driving to merchants, chasing invoices and paperwork. So 4 billable days a week.

46 × 4 = 184 billable days a year.

Step 4: the rate. £53,780 ÷ 184 = £292 a day. Call it £295.

Now compare that to a bloke charging £180 a day because that's what he was on as an employed plumber.

• 184 days × £180 = £33,120 turnover
• Minus £8,780 overheads = £24,340 before tax

He's working 184 days on the tools, plus 46 unpaid admin days, for less than an employed plumber's wage with none of the holiday pay, sick pay or pension. The gap between £180 and £292 across 184 days is £20,608 a year. That's the single biggest number in this article, and it's entirely a quoting decision.

There's more detail on building this properly, including how to handle mixed labour and materials jobs, in the guide to pricing a trade job.

Mistake 3: No variations clause, so every extra is free

Every job has them. "While you're here, could you just..." It's a fair question from the customer's side. They've got a tradesperson in the house and a job on their list.

The trouble is that "just" hides the cost. Moving a radiator 600mm is an hour and a half plus fittings. Swapping the taps they bought after you priced the job is another hour when the tails don't line up. A new isolation valve on a supply you've had to drain anyway is fifteen minutes and £9, but the draining was forty minutes.

Say yes verbally to six of those a year at an average of £340 each and you've given away £2,040 of work. Most trades give away more than that and never see it, because it never appears anywhere as a number.

The fix

A variations clause on the quote, then a variation note before any extra work starts. It doesn't need to be formal. A text message counts as writing.

The "happy to leave it" line matters. It's not an ultimatum, it's a choice, and customers take it fine. What they don't take fine is a final invoice £600 higher than the quote with no warning.

Mistake 4: No expiry date and no price-validity line

You quote a rewire in February. The customer goes quiet. In September they ring up and say they'd like to go ahead at the price you gave them.

Copper's moved. The consumer unit you priced has been superseded. Your diary is full and you'd need to turn other work away. But you gave a written price with no end date, so refusing now makes you look like you're pulling a fast one.

Materials volatility is the real risk here. On a £6,800 rewire where materials are roughly £2,400, a 12% move on materials is £288 straight out of your margin, and 12% over seven months is not unusual for cable and accessories.

The fix

Two lines on every quote.

The second line sounds like it might scare customers off. It doesn't, because it's obviously fair and it gives them an exit. What it does do is let you have a calm conversation about a price rise instead of eating it.

Mistake 5: Taking a week to send it

You do the site visit on Tuesday evening. You're on the tools Wednesday, Thursday and Friday. Saturday is family. Sunday you can't face the laptop. Monday there's a leak somewhere. The quote goes out nine days later, and by then they've had someone else in.

On domestic work the first decent quote through the door wins a lot of the time. Not because it's cheapest. Because the customer has a problem they want gone, and the person who answers first feels like the person who'll turn up.

Round numbers on what slow quoting costs: if you quote 60 jobs a year at an average value of £3,200, and being slow drops your win rate from 40% to 30%, that's six jobs and £19,200 of turnover lost to nothing more than admin timing.

The fix

Price it on site, in the van, before you drive off. Not the polished document, the numbers. Day rate × days, materials with your margin on, contingency. Then the quote itself is a five-minute job rather than an evening's work you keep putting off.

This is the whole reason quoting from your phone matters more than it sounds. Doing it in the driveway while the job's fresh takes about the same time as writing the notes you'd need to do it properly later. The TradeStash app puts your rates, your standard scope blocks and your T&Cs in one place so the quote goes out before you've left the street.

What not to do when you go and fix your quotes

Most trades who read something like this go too far the other way. Four things to avoid.

1. Don't itemise down to the screw. A quote listing 14 lines of fittings at £2.40 each invites the customer to price-check every one and to start supplying their own. Group it: "Supply and fit of first fix pipework, fittings and valves, £680."
2. Don't give a verbal price and "confirm it later". The number they remember is always the lowest one you said out loud, including the one you were thinking aloud about. If you're asked for a ballpark on site, give a range with both ends higher than you think and say the written quote follows.
3. Don't drop your price to win the job. If you knock 10% off a £4,000 quote, you've given away £400 of profit, which on a 20% margin is half the money you were making. Change the scope instead: take out the tiling, take out the making good, keep the rate.
4. Don't copy another firm's quote template blind. Their payment terms, deposit stage and exclusions are built around their cashflow and their trade. Take the structure, write your own numbers. Deposit levels in particular are worth getting right, and there are rules and expectations around how much deposit a builder can ask for.
5. Don't send a quote with no payment terms on it. A price with no "payment due within 14 days of invoice" line is how 47-day payment cycles start. Terms belong on the quote, not just the invoice, so the customer agrees to them before you start rather than after you've finished.

The ten-minute version

If you do nothing else after reading this, do these three things this week.

1. Work out your actual day rate with the four steps above. Write it on a bit of card and stick it in the van.
2. Add the scope, exclusions, variations and validity blocks to your quote template once. They're reusable on every job forever.
3. Set yourself a 24-hour rule on quotes. Price it on site, send it the same evening or the next morning.

None of this makes you more expensive in the eyes of a customer. A quote with a clear scope, sensible exclusions and a fair variations clause reads as more professional than a one-line number, and it gets accepted more often. You're not asking for more money. You're just stopping the leak.