The short answer: an estimate is not usually binding as a price, but the agreement it sits inside is absolutely binding as a contract. Those are two different things, and mixing them up is how tradespeople end up either working for nothing or being reported to trading standards.
Here is what actually binds you, what does not, and what to do when it goes wrong.
What makes a contract, and how little it takes
A contract does not need to be signed. It does not need to be typed. In UK law a verbal agreement to do defined work for a price is a contract, and it is enforceable.
You have a contract when there is an offer, an acceptance of it, something of value going each way, and an intention to be legally bound. On a domestic job that is usually: you said you would fit the boiler for £2,400, they said go on then.
Writing it down does not create the contract. It proves it. That distinction matters, because it explains why so many disputes come down to who sounds more credible rather than to whether an agreement existed.
When an estimate hardens into a fixed price
Three ways an estimate stops behaving like an estimate.
1. It was really an offer. If your document contains one confident number, no qualifying language, no assumptions and no mention that the figure could move, it can be treated as a firm offer regardless of the word at the top. The label does not decide it. The wording does. That is covered in more detail in quote vs estimate.
2. You said something that overrode it. Section 50 of the Consumer Rights Act 2015 says information given to the consumer about the service, which they take into account in deciding to go ahead, becomes a term of the contract. So “the estimate says £3,000 but honestly it won’t go a penny over” can bind you even though your paperwork was careful. Be as disciplined on the phone as you are on the page.
3. Both sides behaved as though the price was fixed. If you took a deposit against a stated total, started work, and never once mentioned that the figure might change, the conduct tells its own story.
The reasonable price rule
Where the price genuinely was not fixed, section 51 of the Consumer Rights Act 2015 says the consumer must pay a reasonable price. Not the estimate, and not whatever you decide to invoice.
Nobody has defined reasonable with a number, and there is no percentage tolerance written into the legislation. In practice the things that decide it are:
- the market rate for that work in your area
- how much additional work was genuinely done, and whether it was foreseeable
- what your estimate said about assumptions and exclusions
- whether you told the customer as the job changed, or at the end
The last one is doing most of the work. An overrun the customer authorised on Tuesday is a variation. The identical overrun revealed on the final invoice is a dispute.
What else the Act requires of you
The price is only half of it. For work done for a consumer, the Consumer Rights Act 2015 also implies terms into the contract that you cannot contract out of:
- Reasonable care and skill (section 49). The work has to be done to the standard of a reasonably competent person in your trade.
- Reasonable time (section 52), where no time was agreed.
- If you fall short, the consumer can generally require repeat performance (section 55), meaning you come back and fix it at your cost, and can seek a price reduction (section 56) if fixing it is impossible or you do not do it within a reasonable time and without significant inconvenience.
Your terms and conditions cannot strip these out. Part 2 of the same Act also means a term that is unfair or not transparent may simply be unenforceable, so an aggressive clause is often worse than no clause at all, because it gives the customer a grievance and gives you nothing.
Variations: the single biggest cause of disputes
Almost every serious argument about money on a domestic job is a variation argument. You found something, you dealt with it, and now nobody agrees what was said.
Work done outside the agreed scope, without the customer’s agreement, is genuinely hard to recover. There was no agreement to pay for it. Being right about the work being necessary does not by itself create a debt.
How to do a change order in sixty seconds
You do not need a formal document. You need a record, made at the time, in writing, that the customer has seen.
A text message is enough:
Hi Mark. Opened up the floor and the joist ends are rotten where the leak has been. Needs two new joist ends and a sister joist, plus a day’s labour. That’s £480 plus VAT on top of the estimate. Can you confirm and I’ll crack on?
Then wait for “yes”. A “yes” in writing on your phone has settled more disputes than any set of terms and conditions.
Three rules:
- Before, not after. A price agreed afterwards is a negotiation. Agreed beforehand it is a contract.
- A number, not a warning. “It’s going to cost more” is not a variation. “£480 plus VAT” is.
- Get the confirmation. Sending it is not the same as it being agreed.
If they say no, stop and put in writing what you have done and what you recommend. You are then documented as having flagged the problem, which matters a great deal if the thing you were not allowed to fix later fails.
Deposits and cancellation
Deposits are normal and reasonable, especially where you are buying materials. Two things to keep in mind.
A deposit clause cannot be a penalty. If a customer cancels, what you keep should reflect what you have actually lost or committed: materials ordered, a slot you cannot refill, work already done. A clause that keeps 50 per cent regardless is likely to be challenged and may be unenforceable against a consumer.
Cancellation rights are the bigger trap. If the contract was agreed in the customer’s home, or anywhere away from your own premises, it is an off-premises contract under the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013. The consumer normally has 14 days to cancel without giving a reason, and you must give them prescribed information, including the cancellation right and a cancellation form, in a durable form before the contract is made.
If they want you to start inside the 14 days, they have to request that expressly. If you never gave the cancellation information at all, your ability to be paid for work done in that period can be seriously compromised, and the failure to provide it is itself an offence. Building the notice into your standard paperwork solves it permanently, and there is a place for it in the estimate template guide.
When it does go wrong
A ladder. Do not skip rungs, and do not start on the top one.
1. Pick up the phone. Most disputes are about feeling ignored. A conversation on day one settles what a letter on day thirty will not.
2. Put your position in writing. Calm, dated, factual. What was agreed, what changed, when you told them, what is outstanding. You are writing for the version of this that has a third party reading it.
3. Offer something concrete. Coming back to fix a defect, a partial credit, a payment plan. Being seen to be reasonable is worth real money later.
4. Alternative dispute resolution. Under the ADR Regulations that came into force in 2015, a trader who cannot resolve a consumer complaint through its own complaints procedure must tell the consumer about a certified ADR provider and say whether it will use it. If you are with a trade body or a scheme such as TrustMark there is usually a route built in, and it is quicker and cheaper than court for both sides.
5. Court, last. For a debt, that means the small claims track and a letter before claim first. The process, the pre-action requirements and the interest position are covered in getting paid on time.
What weakens your position, every time
- No written scope, so nobody can say what was included
- Verbal variations
- Reassuring price talk on the phone that contradicts your paperwork
- No dates on anything
- Overwriting an old estimate instead of issuing a revision
- Going quiet when the customer complains
- Continuing to work while the argument runs, without agreement
What strengthens it
- A scope paragraph the customer accepted in writing
- Assumptions and exclusions stated at the outset
- Photographs, dated, of what you found
- Variations confirmed by text or email before the work
- A record of every time you told them something
- A calm written summary as soon as it turns sour
This is general information about how these rules work in practice, not legal advice about your job. Consumer law changes, and the detail of a particular dispute matters. Check the current position on GOV.UK, talk to Citizens Advice, your trade body or your insurer, and get a solicitor involved when the sum is big enough to be worth it.
The practical version of all this is short: write the scope down, say what you assumed, and confirm every change in writing before you do it. Most of that is paperwork discipline rather than legal knowledge, which is why it is worth having it produced for you: TradeScribe puts the scope, the assumptions and the variation wording on every estimate as a matter of course, rather than only on the ones you had the energy to write properly.