Your rights when a contractor’s price goes up: Ontario’s 10% rule

Under Ontario law, a contractor cannot charge you more than 10% over their estimate without your agreement. Here is how it works, and what to do if it happens.

You got an estimate, the work was done, and the bill is higher. In Ontario, the law has a clear answer for this, and it is on your side.

The rule

Ontario’s Consumer Protection Act, 2002 says that when a business gives you an estimate, it cannot charge more than 10% above it — unless you agree to the higher price first. If the job turns out bigger than expected, the contractor has to stop, tell you the new figure, and get your agreement before carrying on.

What it looks like in practice

Your estimate is $400. The contractor can charge up to $440 without asking.
If the real job would cost $600, they have to put $600 to you before doing the extra work.
If you agree, the 10% is then measured from the new figure.
If they do the extra work first and send the bill after, you are entitled to pay no more than the estimate plus 10%.

Get it in writing

The rule works best when there is a record. An estimate written down, and any change agreed in writing, makes a disagreement short. On Doyo, a pro who finds extra work sends the revised figure in the order chat and waits for your answer — so the record exists by design.

If it has already happened

Pay what the estimate plus 10% comes to, and put your reasons in writing.
Keep the estimate, the invoice and any messages.
If you booked through a platform, report it from the order — held payments can stay held while it is looked at.
Consumer Protection Ontario takes complaints and can help, and Small Claims Court handles disputes up to $50,000.