Extra work on site: get the yes before you pick up the tools
A rotten joist, a seized valve, a socket that isn’t where the drawing said. Jobs grow, and that’s normal. Arguments about the bill aren’t. Here’s how to agree extra work in about two minutes.
Every trade knows the moment. You lift the bath panel and the joist underneath crumbles in your hand. The job you quoted for has just changed, and the next five minutes decide whether the final invoice is a formality or a fight.
Why extras turn into arguments
Clients remember the number on the quote. They don’t remember the conversation on the landing where they said “yeah, go on, do whatever it needs”. When the bill arrives higher than the quote, that conversation is your word against theirs.
The rule is on their side, too. Citizens Advice tells homeowners that a trader can only charge more than a quote if they were told about the extra work and approved it, or if the quote had an obvious mistake.1 So the approval is the whole game. Get it clearly, and get it before you start.
No yes, no extra. It feels awkward for thirty seconds and saves you weeks of chasing.
The two-minute variation
- Stop before you start the extra. Finish making things safe, then pause. Don’t do the work and explain later.
- Show them. Take a photo. People agree to what they can see.
- Price it there and then. Use your hourly rate and your materials markup, and give one number. If you really can’t price it yet, say when you will and don’t start until you have.
- Get the yes in writing. A signature on your phone, a reply to a text or an email all leave a record. A nod doesn’t.
- Keep it separate on the invoice. Give each extra its own reference and line, so the client can see the original quote and the agreed extras side by side.
What to say
Keep it short, explain the risk of leaving it, give the price and the time, and ask a direct question.
“I’ve found a seized valve under the sink. If I leave it, the new tap will probably leak within weeks. Replacing it is £82 and about forty minutes. Do you want me to go ahead? If so, can you sign here so we’re both clear on it?”
If they say no, write that down too. “Client declined replacing the valve” on the job record protects you if the old valve fails next month.
Pricing it on the spot without guessing
The hardest part of an extra is putting a number on it while someone watches. Work it out the same way every time:
- Time at your normal hourly rate, rounded to a sensible block (half an hour, say).
- Materials at cost plus your usual markup.
- VAT on top if you’re registered, shown clearly.
Give one fixed figure for the extra rather than a range. A range invites the client to remember the bottom of it.
When your worker finds it
If you’ve got people on site, decide who is allowed to agree prices. For most small firms the answer is: the owner. Your worker reports what they’ve found, with photos, and you price it and send it to the client. That stops prices being agreed by people who don’t know your margins, and it keeps the client dealing with one set of numbers.
What the record should show
| Field | Example |
|---|---|
| Reference | V-003 |
| What and why | Replace seized isolation valve. Old valve won’t shut off, new tap would leak. |
| Price | £82.00, including parts |
| Time | About 40 minutes, same day |
| Approved by | Sarah Jenkins, signed Tue 13 Oct, 10:14 |
| Photos | Before and after |
How Accepto helps
In Accepto you tap Add extra and say what you found. It writes it up, leaves out anything that’s already in the agreed scope, and prices the rest from your hourly rate and materials markup. You can add photos, and a scanned receipt can stand in for the materials.
Then the client approves: they sign on your phone with their full name, or you send them a link from your phone and they approve online. The record shows who approved it and when, and approved extras go on the final invoice. You price, the client approves, then the work starts.
Try it on your next job.
Accepto is in early access for UK trades and sole traders. Join the list and we’ll email you when it’s your turn.
Sources
General information, not legal or tax advice. Checked October 2026. If you’re unsure how the rules apply to you, speak to an accountant or a solicitor.