The Estimate, the Change Order, the Final Bill: How Ontario’s 10% Rule Reads Your Renovation Paperwork

When a contractor texts that the job will cost more, the Consumer Protection Act already has a view on it. Which of your three pieces of paper exists decides how much of that view you can use.

Halfway through a bathroom job, the message arrives on your phone: “the vanity you picked is back-ordered, the one in stock costs more, OK?” No number. No paperwork. Just a heads-up and an expectation that you will say OK so the crew can keep going.

I’m Arthur Zhao, a real estate broker in Toronto. When a homeowner shows me a message like that, my first question is not “how much more?” It is “show me the paper.” Ontario’s Consumer Protection Act, 2002 has a specific rule for bills that overshoot an estimate, but the rule works through documents: the estimate you started with, whatever you agreed to when the work changed, and the invoice at the end. This piece takes those three pieces of paper one at a time: what each one is in the statute, what the statute makes it carry, and what happens when it is missing.

Paper 1: the estimate

What it is in the statute. Section 10 switches on when “a consumer agreement includes an estimate.” Part II of the Act, where s.10 sits, does not define “estimate.” The Act does define the word in s.55, but only “in this Part,” meaning Part VI, which deals with repairs to motor vehicles and other goods and describes an estimate of “the goods being repaired.” That definition is not built for a kitchen or a bathroom, so I would not borrow it.

The estimate also has to sit inside a consumer agreement between a consumer and a supplier. Section 1 defines a consumer as “an individual acting for personal, family or household purposes,” and says the term “does not include a person who is acting for business purposes.” A supplier is “a person who is in the business of … supplying goods or services.” Section 2(2)(f) takes purchases, sales and leases of real property outside the Act, but s.2(6) adds that, despite (2)(f), the Act applies where a supplier supplies goods that are not part of the real property when the agreement is made but become part of it under the agreement. My reading, and it is an inference rather than a ruling, is that hiring someone to renovate the home you live in is a services contract, not a purchase or sale of the house, so (2)(f) does not take it out of the Act.

What the statute makes it carry. The estimate is the baseline. Every later number gets measured against it. Take a hypothetical: an estimate of $18,000 puts the s.10(1) ceiling at $19,800. A bill of $21,500 is past that line, and s.10(2) then lets you require the work at the estimated price, $18,000.

What happens if it is missing. If no estimate was ever given, s.10 has nothing to measure against. If one was given but is vague (“bathroom, about eighteen”), s.11 helps a little: any ambiguity in a consumer agreement the supplier provided that allows more than one reasonable interpretation “shall be interpreted to the benefit of the consumer.” Section 7(1) adds that the Act’s rights apply “despite any agreement or waiver to the contrary,” so a line in the contract saying the estimate can be exceeded without limit does not, on the text, switch s.10 off.

If the contractor sat at your kitchen table to sign you up, there is a second layer. Section 20 defines a direct agreement as a consumer agreement negotiated or concluded in person somewhere other than the supplier’s place of business (or a market, auction, trade fair, agricultural fair or exhibition). Where your total potential payments exceed $50 (s.41(1) with O. Reg. 17/05, s.34), s.42(1) requires the agreement to be in writing and delivered to you, and O. Reg. 17/05, s.35(1) lists what it must set out, including a fair and accurate description of the goods and services, the total amount payable, and an itemized list of prices. A direct agreement also carries a 10-day cancellation right under s.43(1); the cooling-off rules have their own article, linked under related reading below.

Paper 2: the change order, or the text message that stands in for one

What it is in the statute. Section 10(3) is the one place the Act lets the number move: “Nothing in this section prevents a consumer and a supplier from agreeing to amend the estimate or price in a consumer agreement, if the consumer requires additional or different goods or services.” Two conditions are packed into that sentence. There has to be an agreement to amend, and the trigger is that the consumer requires additional or different work.

What the statute makes it carry. Whatever you agree to mid-job becomes the new reference point. That is why the reply to “the vanity you picked is back-ordered, the one in stock costs more, OK?” matters. The Act’s text does not mention substitutions the contractor proposes; it speaks of you requiring something additional or different. Whether a one-word “OK” to an open-ended message amounts to agreeing to an amended price, and at what amount, is not something the wording of s.10(3) settles on its own. A reply that names the extra work and a number leaves far less to argue about.

Section 10 does not say the amendment has to be in writing. If the original contract was a direct agreement, s.42(1) required that agreement to be in writing; the Act’s text, as I read it, does not separately say whether a later amendment counts as a new direct agreement, so I would not rely on either answer without advice.

What happens if it is missing. If there is no record of an agreed change, the final bill has to be compared with the original estimate alone, and the conversation turns into your recollection against the contractor’s. If there is a record that is unclear, s.11 again reads ambiguity in a supplier-provided agreement in your favour, but only to the extent the document is genuinely open to more than one reasonable reading.

Paper 3: the final invoice

What it is in the statute. The invoice is the “charge” that s.10(1) regulates. It is where the rule is tested: the amount charged against the estimate, as amended under s.10(3) for any extra or different work you required.

What the statute makes it carry. If the charge exceeds the estimate by more than 10 per cent, s.10(2) gives you the right to require the work at the estimated price. Separately from price, s.9(1) deems the supplier to warrant that services supplied under a consumer agreement “are of a reasonably acceptable quality,” so an invoice for work that falls short of that standard raises a second, independent issue.

If the contractor will not move, the Act names two routes. Section 100(1): where a consumer has a right to commence an action under the Act, the consumer “may commence the action in the Superior Court of Justice.” Section 105(1): the Ministry may receive complaints about conduct that may contravene the Act and may “make inquiries, gather information and attempt to mediate or resolve complaints.” According to the Government of Ontario’s “Filing a consumer complaint” page (updated December 5, 2025), home renovation and maintenance is one of the complaint types it can assist with, the Ministry recommends writing to the business first, and it says it will contact you within 15 business days of a complaint.

What happens if it is missing. An invoice with one lump sum and no breakdown makes the comparison with the estimate and any change order harder to do line by line. Ask for the breakdown before you pay the balance, not after.

Which Act you are reading today

The rules above come from the Consumer Protection Act, 2002, which is the law in force. Ontario has passed a replacement, the Consumer Protection Act, 2023, but e-Laws carries this note at the top of it: “THIS ACT IS NOT YET IN FORCE. It comes into force on a day to be named by proclamation of the Lieutenant Governor.” The 2002 Act carries the matching note that it “is repealed on a day to be named by proclamation.” The estimate rule survives the rewrite: s.12(1) of the 2023 Act says that if a consumer contract includes an estimate, the supplier shall not charge more than the estimate “by more than 10 per cent,” and s.12(2) and (3) repeat the estimated-price right and the additional-or-different-work exception. I am not going to guess when the new Act will be proclaimed; there is no official date to cite.

Three papers, checked before the last payment

Work through these by document, not by date. If one of the three papers does not exist yet, the items under it tell you what to create.