Cohabitation Agreements in Ontario: What Common-Law Couples Need to Know

You've moved in together — maybe you've been together for years — and the word "married" has never come up. That's fine, but here's something many Ontario couples don't realize: unlike spouses, common-law partners have no automatic right to share in each other's property when a relationship ends. The Family Law Act's equalization rules that protect married people simply do not apply to unmarried couples.

A cohabitation agreement is the contract that fills that gap. It lets two people who live together outside of marriage define their financial relationship — what they own, what they owe, and what happens if they split. Getting one in place before or early in a cohabitation is almost always easier (and cheaper) than fighting over property in court years later.

What Is a Cohabitation Agreement?

Under Ontario's Family Law Act, a cohabitation agreement is a domestic contract between two people who are cohabiting or intend to cohabit and are not married to each other. Like all domestic contracts, it must be:

• In writing
• Signed by both parties
• Witnessed by at least one person for each signature

It can address ownership of property, support obligations, and financial arrangements — both during the relationship and if it ends.

Why Common-Law Couples Are Vulnerable Without One

Ontario's property-division regime for married spouses does not extend to unmarried couples. When a common-law relationship ends:

• Each person keeps what they own. Assets held in one person's name stay with that person, regardless of how long the couple was together or how much the other person contributed informally.
• There is no automatic equalization payment based on accumulated wealth during the relationship.
• The only property remedies available are general civil law claims — such as unjust enrichment (where you show you contributed to someone's asset without fair compensation) or resulting trust. These claims are expensive, uncertain, and require litigation.

The classic scenario: a couple lives together for ten years. One partner owns the home and has investments. The other earns less but manages the household and contributes to joint expenses. The relationship ends. Without a cohabitation agreement or a successful court claim, the lower-earning partner may walk away with very little despite a decade together.

What a Cohabitation Agreement Can Cover

Property Owned Before Moving In

The agreement can specify that each person's pre-relationship assets remain their own — savings accounts, investment portfolios, vehicles, personal property.

Property Acquired During Cohabitation

The parties can agree that jointly-titled property is shared equally, or in whatever proportions reflect their actual contributions. They can also agree that everything bought in one person's name remains solely that person's.

The Shared Home

If you're renting, the agreement can address what happens to the lease. If one partner owns the home, the agreement can define whether the other acquires any interest over time, and what happens to any improvements funded by the non-owner.

Spousal Support

Common-law partners can owe each other support after a relationship ends, provided they cohabited for at least three years or have a child together (as of writing — verify current thresholds). A cohabitation agreement can address whether support will be paid, how it's calculated, and for how long.

Debts

The agreement can clarify who is responsible for debts incurred before or during the relationship.

Day-to-Day Financial Arrangements

Many couples use cohabitation agreements to address practical matters: how rent or mortgage is split, who pays utilities, whether there's a joint account for household expenses.

What a Cohabitation Agreement Cannot Cover

Like all domestic contracts, a cohabitation agreement cannot:

• Limit a child's right to support — that belongs to the child and the court
• Bind a court on decision-making responsibility or parenting time (what is colloquially called custody and access) — those decisions are made at the time of separation based on the child's best interests
• Waive obligations in a way that is unconscionable or that a court finds would cause serious hardship

The Role of Independent Legal Advice

Independent legal advice (ILA) is not strictly required by statute, but it is essential in practice. If a cohabitation agreement is ever challenged — and they often are — a court will look closely at whether:

1. Both parties fully understood the terms
2. Both had adequate time to review and ask questions
3. Both received advice from a lawyer who had no conflict of interest

Each partner should retain their own lawyer. The drafting lawyer cannot act for both. ILA certificates signed by each lawyer become strong evidence of voluntary, informed consent.

What Happens If You Later Get Married?

A cohabitation agreement automatically converts into a marriage contract if the couple marries — the Family Law Act says so explicitly. This means:

• The agreement continues in force after marriage
• Its property and support provisions apply as a marriage contract
• You do not need to sign a new document just because you got married — though you should review the existing agreement to make sure it still reflects your intentions

Many couples do choose to update their agreement when they marry, particularly if circumstances have changed significantly.

Frequently asked questions