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Cohabitation Agreement in Ottawa: Ontario and Quebec Border Couples

Living in Ottawa and thinking of moving to Gatineau? Learn how Ontario treats a cohabitation agreement and why a move to Quebec calls for fresh advice.

Family Law5 min readTSLBy the Treadstone Law Team · OntarioUpdated October 28, 2026
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Key takeaways
  • An Ontario cohabitation agreement must be in writing, signed and witnessed to be enforceable.
  • For a contract made outside Ontario, its proper law governs its validity and effect, but Ontario's grounds for setting aside still apply here.
  • Parenting provisions in a cohabitation agreement cannot be enforced as agreed.
  • Quebec has its own family law rules, so a move across the river is a reason to get advice before relying on an Ontario agreement.

Ottawa couples live next to a provincial border. It is common to work in one province and live in the other, or to rent in Ottawa now and think about buying in Gatineau later. A cohabitation agreement signed in Ontario may then be asked to do more than you first expected.

This article explains how Ontario treats cohabitation agreements and what to think about if you may relocate to Quebec. It does not describe Quebec law in detail. Quebec's rules are separate and should be confirmed with a Quebec source or lawyer.

What an Ontario cohabitation agreement is

Two people who are cohabiting or intend to cohabit, and are not married, may make a cohabitation agreement covering rights and obligations during cohabitation, on ceasing to cohabit, or on death, including ownership and division of property and support. If you later marry each other, the agreement is deemed a marriage contract.

It is a domestic contract, so it is unenforceable unless made in writing, signed by the parties and witnessed. Ontario guidance adds that each partner should use a different lawyer and exchange financial information, and that the agreement cannot decide decision-making responsibility or parenting time for children.

Why it matters in Ontario at all

Without an agreement, unmarried partners are not 'spouses' for property equalization. Common-law couples are not legally required to split property acquired while living together. Spousal support is different: it extends to unmarried people who cohabited continuously for at least three years, or who are in a relationship of some permanence and are parents of a child.

When one of you dies, an unmarried partner has no intestate share. An agreement can address what happens on death. These are the gaps that an Ottawa couple living in Ontario is trying to fill.

How Ontario treats an agreement made elsewhere

If you sign an agreement outside Ontario, or later move away, Ontario law has a specific rule. The essential validity and effect of a domestic contract is governed by its proper law. Even so, the Ontario grounds for setting aside a support waiver and for setting aside a contract still apply in Ontario to such contracts, and parenting-decision provisions are not enforceable in Ontario.

The grounds include failure to disclose significant assets or debts, not understanding the nature or consequences of the contract, and other contract-law grounds. A support provision or waiver can be set aside if it results in unconscionable circumstances, if the dependant qualifies for public support allowances, or if there is a default in payment at the time of the application.

Which province's courts hear a dispute, and which law applies, depends on where you live and on what your agreement says about governing law. That is a question to put to a lawyer before you move, not after.

If you may move to Gatineau

Quebec has its own rules for couples who live together without marrying. Do not assume that your Ontario rights, such as spousal support after three years of cohabitation, carry over unchanged. The rules in Quebec are different and are set by Quebec law, which this article does not describe.

QuestionWhy it matters if you cross the border
Which law governs the agreement?The proper law of the contract governs its validity and effect, with Ontario's set-aside grounds still applying in Ontario.
Which court would hear a dispute?Depends on where each of you lives and what the agreement says. Confirm with a lawyer.
Does your property plan still fit?An Ontario agreement's property terms were written with Ontario law in mind. Quebec rules may treat the same facts differently.
Do your wills and powers of attorney still work?Ontario documents were made under Ontario rules. Have a Quebec lawyer review them.

If a move is realistic, consider asking the lawyer who drafts the agreement to address the move directly, for example by including a governing-law clause and a plan for review on relocation. Whether that is the right approach depends on the facts.

Other places the definition of 'common-law' differs

There is no single date on which a couple becomes common-law. Under the Income Tax Act, a common-law partner is someone who has cohabited in a conjugal relationship for the 12-month period ending at that time, or is the parent of a child of whom the taxpayer is a parent. For the Canada Pension Plan survivor's pension, it is at least one year of living together in a conjugal relationship. For support under the Family Law Act, it is three years or a child with a relationship of some permanence. Because the tests differ, a move or a change in how you live can affect your status under some laws and not others.

What to do next

Frequently asked questions

Will my Ontario cohabitation agreement still work if we move to Quebec?

It depends. A contract made outside Ontario is governed by its proper law, but Ontario's grounds for setting aside still apply in Ontario. What a Quebec court would do is a Quebec law question, so get Quebec advice before you move.

Does Ontario enforce parenting terms in a cohabitation agreement?

No. Parenting provisions, including decision-making and parenting time, cannot be enforced as agreed. A child support term can also be disregarded if it is unreasonable under the guidelines.

What makes a cohabitation agreement valid in Ontario?

It must be in writing, signed by both parties and witnessed. It is more likely to hold up with full financial disclosure and a real understanding of its terms.

Do we need an agreement if we have lived together over three years?

After three years of continuous cohabitation you may be treated as spouses for support, but not for property equalization. An agreement can set out your property and support terms in advance.

This article is general information, not legal advice. Reading it does not create a lawyer-client relationship. Ontario laws, tax rates, and government programs change, and how the law applies depends on your specific facts. For advice about your situation, speak with a licensed Ontario lawyer. Treadstone Law is licensed by the Law Society of Ontario — reach us at 1-844-900-1070 or start a file online.

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