When the job changes: getting paid for work you didn't quote for

Every trade has the same moment. The board comes off, the floor comes up, the plaster comes back on the scraper, and the job in front of you is not the job you priced.

What you're allowed to do about that is more constrained than most traders think in one direction and much less constrained in another — and the part that decides whether you actually get paid isn't the price at all. It's a piece of paperwork almost nobody does.

First, the rule that doesn't exist

Somewhere in every trade forum thread on this subject, someone says an estimate can be exceeded by 10%, or 15%, without needing to ask.

There is no such rule in UK law. Not in statute, not in official guidance, not in any trade code of practice. The Trading Standards guidance for services doesn't contain a percentage. Neither does the Citizens Advice guidance. Neither do the codes of conduct published by TrustMark, Which? Trusted Traders, Checkatrade or MyBuilder — several of which address extra work directly and all of which answer it the same way, with authorisation rather than a tolerance.

The figure is real law — just not here. Alberta's Consumer Protection Act makes it an unfair practice to charge more than 10% above an estimate, to a maximum of $100, without the consumer's express consent, and Ontario has its own version. Several American states have the same idea for motor repairs: Illinois and Maryland at 10%, Virginia at 10% with a 20% allowance for cars over 25 years old, Minnesota expressed the other way round as a 110% ceiling. California, which gets cited for it constantly, has no percentage at all — just a rule that any increase needs fresh authorisation.

So the rule exists. It's Canadian and American consumer legislation that has drifted into British forums and trade blogs, some of which now attribute it directly to a section of the Consumer Rights Act that contains no number of any kind.

If you've been working to "I can go 10% over without asking", you've been working to the law of Alberta.

Quote and estimate are not the same promise

The distinction is real, and it is about what you've offered rather than what you called it.

A quote is an offer of a fixed price. Once the customer accepts it, you have a binding contract at that figure. You cannot charge more because the job was harder than you expected, and you specifically cannot charge more because your own costs went up between quoting and doing it. That risk is the thing a fixed price is for; it's why customers like them and why you're entitled to price it in.

An estimate is your best guess and doesn't fix the price. That does not make it a free hand. The final figure has to be reasonable — and the law deliberately doesn't define reasonable, which means it's a matter of fact to be argued about rather than a number you can look up. An estimate that bore no relation to the eventual bill has a second problem: it may have been misleading when you gave it.

The practical read: if you know the price, quote. If you genuinely don't, estimate — and say plainly what would move it, because "£100, possibly more depending on the state of the timber" is an honest estimate and "£100" followed by an invoice for £260 is a fight.

One thing not to take from "there's no percentage": it does not follow that anything reasonable goes. The Consumer Rights Act treats what you said or wrote about the service as a term of the contract wherever the customer took it into account in deciding to go ahead — and a change to it is not effective unless it is expressly agreed. An estimate the customer relied on is therefore already part of the deal, and moving off it needs their agreement rather than a justification. The reasonable-price rule is a fallback for when no price was set at all, not a licence to revise one that was.

Extra work needs agreement, and the agreement comes first

The rule underneath all of this is short. You carry out the work that was agreed. If more is needed, you tell the customer and get their agreement before you do it.

The official guidance on the Consumer Rights Act works exactly this example: a painter quotes £100 to paint a fence, saying it may be more depending on the condition of the wood. On arrival the timber is old and will take more paint, so the price will be £120. He explains; the customer recognises the problem and agrees to the new price. Nothing has been breached. That is the whole mechanism — explain, agree, then work.

Reverse the order and you have done work nobody asked for and are asking to be paid for it after the fact. A customer who says no to that is on strong ground.

The agreement itself doesn't legally have to be written. A verbal variation binds. What writing gives you is evidence, and evidence is the entire game when the argument arrives four weeks later and two people remember a hallway conversation differently.

Two things worth knowing about your own paperwork here. If your terms say variations must be agreed in writing, that clause works — the Supreme Court settled in 2018 that a no-oral-modification clause does what it says, so a verbal agreement to an extra may not bind if your own contract required writing. And a blanket clause reserving the right to charge more if you find extra work is exposed from the other side: a term letting one party change the price unilaterally without a specified valid reason, or without the customer being able to cancel, sits squarely on the list of terms that get struck out as unfair. A specific, transparent mechanism is fine. A blank cheque isn't.

The bit almost every trader has backwards

Here's where the real risk sits, and it isn't the price.

Most traders believe that agreeing work at a customer's house always gives them a 14-day cooling-off period, and treat it as a nuisance attached to domestic work generally. Both halves of that are wrong.

Leaving a quote for them to think about is not an off-premises contract. You visit, you look at the job, you leave or later send a quotation, and they accept it when they're ready. Trading Standards guidance is explicit that this is an on-premises contract — no cancellation right, and a shorter information list.

Agreeing the extra on the spot is. Standing in the hallway with the floor up, saying it needs another circuit, and the customer saying go on then — that is a contract concluded in the simultaneous physical presence of both of you, somewhere that isn't your business premises. Which is the textbook definition of an off-premises contract, with a 14-day right to cancel attached.

So the paperwork discipline is upside down in most businesses. The original job — quoted, considered, accepted at leisure — often needs none of it. The extra, agreed in ninety seconds with your knees on a joist, is the one carrying rights that need to be given in writing.

What it costs to get that wrong

This is the part worth reading twice, because the downside isn't a telling-off.

If the work is an off-premises contract, you must not start supplying it before the cancellation period ends unless the customer has made an express request to start early — and for off-premises work, that request has to be in a durable medium. Paper, email, a text message. Something addressed to them, storable, and reproducible unchanged. Not a nod.

Where that request wasn't obtained, or where you never gave the cancellation information in the first place, the regulations say the consumer bears no cost for the service supplied during the cancellation period. Not a reduced amount. No cost.

Alongside that: entering an off-premises contract without giving the required cancellation information is a criminal offence, punishable by a fine — unlimited in England and Wales, capped at £5,000 in Scotland. And where the cancellation information is never given at all, the 14-day window doesn't quietly expire; it extends by up to twelve months.

Set against that, raising the extra as its own small written quote and getting it accepted before you start costs you about four minutes.

That asymmetry is the actual argument. Not that the law definitely treats every on-site extra as a fresh contract — see below, because it doesn't clearly say — but that the cost of being careful is four minutes and the cost of being wrong is the whole invoice plus a criminal offence.

Where the law genuinely isn't settled

Being straight about the limits of this, because plenty of pages on the subject are not.

For extras agreed during an urgent repair visit, the position is clear and comes from the regulations themselves. An emergency call-out is exempt from cancellation rights — but that exemption expressly does not extend to services in addition to the urgent repairs, or to goods beyond the replacement parts needed for them. The government's own guidance works the example: a plumber called out to a burst pipe who also agrees to lag the hot water cylinder while he's there. The customer can cancel the lagging the next day, and the guidance says he should have given her the cancellation form before agreeing to supply it.

For an extra on an ordinary, non-emergency job — where the original contract was properly papered and you're on site doing it — there is no authority either way. No case law, no guidance addressing it, and Trading Standards' own two guidance streams handle it differently: the off-premises material treats on-site extras as new contracts, while the services material discusses mid-job changes purely as a variation question and never mentions cancellation at all.

Anyone telling you this point is settled hasn't looked. The reason to paper it anyway is the asymmetry above, not certainty.

Getting paid for it afterwards

If the extra was agreed properly and they still won't pay, the recovery route is the ordinary one. Worth knowing what doesn't help: statutory late-payment interest, the 8%-over-base one people mention, applies only where both sides are acting in the course of a business. It works against a landlord, a letting agent or a main contractor. It does nothing at all against a homeowner. Against a consumer you're relying on an interest term in your own contract, and that term has to be fair to be worth anything.

When a customer won't pay covers the escalation, and whether small claims is worth it covers the end of the road. One deadline to have in mind while you're deciding whether to bother: you have six years to sue on an unpaid bill in England and Wales, five in Scotland — and the Scottish version doesn't merely bar the claim, it extinguishes the debt.

In Scotland

Most of this is UK-wide — the Consumer Rights Act and the cancellation regulations both apply across all four nations, so the 14 days, the durable medium and the offence are the same wherever you work.

Three differences worth holding. A variation needs no consideration in Scots law; the Requirements of Writing (Scotland) Act says so directly, where in England you'd be looking for something given in return. The fine for the information offence is capped at £5,000 rather than unlimited. And the time limit to chase the money is five years rather than six, with the debt extinguished rather than just unenforceable.

What to actually do on site

The version that fits into a real job:

1. Stop before you do it. The moment the extra is optional rather than unavoidable, it's a decision the customer has to make, not one you can make for them.
2. Price it separately. Not "the job's gone up to £780" — the original £600 plus £180 for the additional circuit. A customer who can see what changed argues far less than one handed a bigger number.
3. Put it in writing before you start, however briefly. A second quote, or a text setting out what's needed and what it costs.
4. Get something back in writing. "Yes go ahead" by text is a durable medium and takes them nine seconds.
5. If you agreed it in their home, give the cancellation notice too. The second quote settles the price; it is not the same as the cancellation information, and getting a "yes" is not the same as the express request to start inside the 14 days. You need the notice, a cancellation form they can use, and — if you're starting before the fortnight is up — their request to do so, with the acknowledgement that the right goes once the work is finished. The quote template generates all of that if you tell it where you agreed the work.
6. Then do the work, and invoice the two things as two lines.

Steps 4 and 5 are the ones that get skipped, and they're the ones carrying the money.

If the customer says no, that's a legitimate answer to an extra they didn't ask for. Write down what you found and that they declined it — particularly where it's a safety matter — and finish the job you were actually contracted to do.

Where the software fits

A second quote is the sanctioned version of all of this, so it's worth having a way to raise one that doesn't mean an evening at a laptop.

In grafter.ly, a job holds more than one quote. Price the extra as its own quote against the same job, send it, and the customer accepts it on a link by typing their name — which timestamps what they agreed to and gives you the written record, on the phone in your hand, before you pick the tools back up.

Be clear about what that acceptance is and isn't. It is evidence that the customer agreed this price for this scope, on this date, which is the thing most variation arguments turn on. It is not a cancellation notice, a cancellation form or an express request to start early — the acceptance screen doesn't ask for any of those, and where the 14-day right applies you still have to give them yourself. There's no dedicated variation feature either, and I'd rather say so than dress the second quote up as one.

You can try it free for 30 days, no card to start.

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Sources. The quote/estimate distinction, the requirement to get agreement before carrying out extra work, and the on-premises versus off-premises position are from Business Companion, the official Trading Standards guidance, and Citizens Advice. The fence-painting example is from the government's Consumer Rights Act services guidance. Cancellation rights, the durable-medium requirement for an early start, the no-cost consequence and the offence are regulations 19, 29, 31, 36 and 28 of the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013; the burst-pipe example is from the government's implementing guidance. Unfair terms are section 62 and Schedule 2 of the Consumer Rights Act 2015; the no-oral-modification point is Rock Advertising v MWB [2018] UKSC 24. Late-payment interest is section 2 of the Late Payment of Commercial Debts (Interest) Act 1998. Scottish variation is the Requirements of Writing (Scotland) Act 1995 s.1; prescription is the Prescription and Limitation (Scotland) Act 1973 s.6. The absence of any percentage tolerance was confirmed against those sources plus the TrustMark, Which? Trusted Traders, Checkatrade, MyBuilder and Motor Ombudsman codes; the overseas rules quoted are Alberta's Consumer Protection Act s.6(2)(e) and Virginia Code § 59.1-207.3. That information you give becomes a contract term, and that changing it needs express agreement, is section 50. Everything above was checked on 8 September 2026. It describes how these rules work in general; it is not advice on your contract, and a dispute with real money in it is worth an hour of someone's time on the actual facts.