Converting a Cohabitation Agreement to a Marriage Contract in Ontario

You moved in together, put a cohabitation agreement in place, and have now decided to get married. Congratulations — and here's something your cohabitation agreement didn't tell you: under Ontario's Family Law Act, that agreement doesn't disappear when you exchange rings. It converts automatically into a marriage contract.

This is genuinely good news if your agreement was well-drafted and still reflects your situation. It's less welcome news if the agreement is outdated, was never updated to reflect changed circumstances, or was drafted when your financial lives looked very different than they do today.

Understanding what happens to a cohabitation agreement when you marry — and what, if anything, you need to do about it — is one of the smarter pre-wedding legal conversations you can have.

The Automatic Conversion Rule

Ontario's Family Law Act states plainly that a cohabitation agreement between two people who subsequently marry becomes a marriage contract. The document doesn't need to be re-signed, re-witnessed, or submitted to any authority. Marriage is the triggering event, and the agreement's terms continue in force as if they had been made as a marriage contract.

This means:

• Property provisions in the cohabitation agreement continue to apply to the marriage
• Support provisions carry forward
• Any financial disclosure made at the time of the cohabitation agreement is treated as the disclosure basis for the now-marriage contract

What changes is the legal regime surrounding the agreement. As married spouses, you are now subject to Ontario's equalization rules, the matrimonial home provisions, and the other protections and obligations of the Family Law Act that apply to married people but not to cohabiting common-law couples.

Why the Conversion Matters — and Why It Might Not Be Enough

The automatic conversion is convenient, but it creates an important question: does your cohabitation agreement actually address the right things now that you're married?

Cohabitation agreements are typically drafted to fill the gap that exists in Ontario law — common-law partners have no automatic property-sharing rights, so the agreement creates a framework. Marriage contracts, by contrast, are used to modify or opt out of the protections Ontario law automatically provides to married spouses.

This means the issues addressed in a typical cohabitation agreement and a typical marriage contract are sometimes quite different:

A cohabitation agreement that says "each person keeps what they own" functions very differently once you're married, because marriage creates equalization rights that didn't previously exist. That same clause, now operating as part of a marriage contract, would be an agreement to opt out of equalization — which is a valid choice, but it may or may not be what you intended.

What to Review Before (or Shortly After) the Wedding

1. Does the Agreement Address the Matrimonial Home?

Marriage creates special rules around the matrimonial home — including that a non-owning spouse has certain possession rights and that the home may not get the benefit of a pre-marital deduction in equalization. Review whether the agreement adequately addresses your shared home given these new rules.

2. Does the Property Division Still Make Sense?

What did each of you own when you signed the cohabitation agreement? What do you own now? If one party has significantly more assets today — or if you've built up shared assets together — the original terms may be stale.

3. Has Your Financial Disclosure Been Updated?

Courts look at the disclosure made at the time the contract was signed. If you signed the cohabitation agreement three years ago and your financial picture has changed substantially, the adequacy of that original disclosure may be a concern.

4. Does the Agreement Cover What Only Applies to Married Couples?

Marriage creates rights like the right to equalization on death and rights under the Succession Law Reform Act. A cohabitation agreement almost certainly didn't address these because they didn't apply at the time. If they're relevant to your situation, an amendment or a new agreement may be worth considering.

5. Is the Agreement Still Fair?

The test isn't just whether the terms were fair when you signed — it's whether they remain fair to enforce given how life has changed. A fresh review is an opportunity to confirm both parties are still comfortable with the terms.

Options When You Get Married

Option 1: Do nothing. The cohabitation agreement converts automatically and continues in force. This is fine if the agreement was carefully drafted, your circumstances haven't changed significantly, and both parties are satisfied with the terms.

Option 2: Have an Ontario family lawyer review the existing agreement. This is the minimum recommended step for anyone marrying with an existing cohabitation agreement. A lawyer can identify gaps, potential enforceability concerns, and whether any provisions need updating.

Option 3: Amend the agreement. Add provisions that address marriage-specific issues — the matrimonial home, equalization, estate rights — while keeping the core terms.

Option 4: Terminate and replace. If the original agreement was poorly drafted, outdated, or no longer reflects your situation, start fresh with a marriage contract that is purpose-built for your current circumstances.

Frequently asked questions