A cohabitation agreement is for unmarried partners; a marriage contract is Ontario's name for a prenup. Both must be in writing, signed and witnessed (Family Law Act s. 55). What they cover, legal advice, and who can witness.
Last updated: October 13, 2026
Cohabitation Agreement Ontario and Marriage Contracts (Prenups): How to Sign
Quick answer: A cohabitation agreement is a contract between two people who live together, or plan to, and are not married to each other (Family Law Act s. 53). A marriage contract is Ontario's legal name for a prenup, and it can be signed before or after the wedding (s. 52). Both are domestic contracts, enforceable only if made in writing, signed by both of you and witnessed (s. 55(1)). The Act does not require a notary, a set number of witnesses, or signing at the same time. What protects the contract later is full financial disclosure and separate legal advice (s. 56(4)). Minute Notary witnesses these agreements in person on a mobile visit; a notary does not draft them or give legal advice.
Couples usually think about a cohabitation agreement when they move in together or buy a home, and about a prenup when they set a wedding date. Either way, the question is what each of you keeps, shares and owes if the relationship ends, written down so it holds up.
If you are still drafting, our free cohabitation agreement template lays out the usual sections. For a question about your own document, contact us or call (613) 434-5555.
Key Takeaways
| Question | Answer | Where it comes from |
|---|---|---|
| Which contract do we need? | Unmarried and living together: cohabitation agreement. Engaged or married: marriage contract | Family Law Act ss. 52(1), 53(1) |
| What if we marry later? | The cohabitation agreement is deemed to be a marriage contract | s. 53(2) |
| When is it binding? | Only when made in writing, signed by both parties and witnessed | s. 55(1) |
| Does it need a notary? | No. The Act names no witness and no number of witnesses | s. 55(1) |
| What can it not decide? | Decision-making responsibility and parenting time; a spouse's matrimonial home rights | ss. 52(1)(c), 52(2), 53(1)(c) |
| Can a court set it aside? | Yes: undisclosed significant assets or debts, a party who did not understand it, and more | s. 56(4) |
Cohabitation Agreement vs Marriage Contract (Prenup)
Both are domestic contracts under Part IV of the Family Law Act (s. 51), alongside separation agreements. What differs is your status when you sign.
| Cohabitation agreement (s. 53) | Marriage contract, "prenup" (s. 52) | |
|---|---|---|
| Who can make it | Two people cohabiting or intending to, and not married to each other | Two people married to each other or intending to marry |
| When | Before moving in, or while you live together | Before or after the wedding |
| If you marry each other | Deemed to be a marriage contract (s. 53(2)) | Already is one |
"Prenup" is not the legal term in Ontario. The Act says marriage contract, and your lawyer will use that name.
You can sign one after the wedding. Section 52(1) covers two people who "are married to each other or intend to marry", so a contract signed after the wedding (a "postnup") is still a marriage contract.
Married couples do not sign a cohabitation agreement with each other. Section 53 is only for people not married to each other. Once you have separated, the contract is a separation agreement (s. 54); see our separation agreement guide.
Why Unmarried Couples Sign One
The Family Law Act treats married and unmarried couples differently, and that is the main reason cohabitation agreements exist.
- Property. The Act defines "spouse" as either of two people who are married to each other (s. 1(1)). The equalization of net family property (Part I, s. 5) and the matrimonial home rules (Part II) use that definition, so they do not apply to unmarried partners. Without an agreement, property generally stays with the partner who owns it; a partner who contributed to it is left with fact-specific court claims, covered in our common-law rules in Ontario guide.
- Support. For support only, Part III widens "spouse" to unmarried partners who have cohabited continuously for at least three years, or who are in a relationship of some permanence and are the parents of a child together (s. 29).
A cohabitation agreement lets you set your own rules for both. A common case is the home one partner owned before the other moved in: the agreement can confirm it stays with the owner, or set out how the other partner shares in it. If you later marry each other, the agreement becomes a marriage contract (s. 53(2)) and the matrimonial home limit in s. 52(2), below, then applies to it.
For married couples, the default runs the other way. Equalization applies when spouses separate with no reasonable prospect of reconciling, when they divorce, and when one of them dies (s. 5). A marriage contract is how spouses change that: they can agree that property is not to be included in a spouse's net family property (s. 4(2), paragraph 6), and the contract prevails over the Act on the same matter unless the Act provides otherwise (s. 2(10)).
What the Agreement Can and Cannot Cover
Sections 52(1) and 53(1) list the same four kinds of terms: ownership in or division of property, support obligations, the right to direct the education and moral training of your children, and any other matter in the settlement of your affairs.
The Act also sets limits:
- Parenting arrangements. Neither contract can decide decision-making responsibility or parenting time for your children (ss. 52(1)(c) and 53(1)(c)). A court can also disregard a term about a child's education or moral training in the child's best interests (s. 56(1)), and a child support term that is unreasonable under the child support guidelines (s. 56(1.1)).
- The matrimonial home. A marriage contract term that limits a spouse's rights under Part II (Matrimonial Home) is unenforceable (s. 52(2)). Those rights include each spouse's equal right to possession (s. 19) and the rule that a spouse cannot sell or mortgage an interest in it without the other spouse joining in or consenting (s. 21).
- Chastity clauses. A term that makes a right on separation depend on a party "remaining chaste" is unenforceable (s. 56(2)). A term tied to a party marrying or living with someone else is not affected by that rule.
- Support waivers. A court can set aside a support term or a waiver of support if it results in unconscionable circumstances, if the person qualifies for support from public money, or if support under the contract is in default, even if the contract says otherwise (s. 33(4)).
The Signing Rule: Writing, Signatures, a Witness
Section 55(1) is short: a domestic contract, and an agreement to amend or rescind one, is unenforceable unless "made in writing, signed by the parties and witnessed."
- In writing. A spoken promise before the wedding is not a marriage contract.
- Signed by the parties. Both of you sign. Many lawyers also have each party initial every page.
- Witnessed. Someone watches each signature being made, then signs as the witness.
What the section does not say:
- Who the witness must be. Choose an adult who is not a party and has nothing to gain from the agreement; a parent who helped with the down payment invites an argument later. Our guide to who can witness a signature in Ontario covers the general rules.
- How many witnesses. Follow the witness lines in your agreement, or the arrangement your lawyer drafted for. The notary can be the witness.
- That you must sign together. Each of you can sign at a separate appointment, as long as each signature is witnessed.
- That a notary is needed. A notary is simply a witness who checks government photo ID and records who signed.
The rule covers changes too: an update after buying a home or having a child, or an agreement to cancel the contract, must also be in writing, signed and witnessed.
What Makes a Court Set an Agreement Aside
Under section 56(4), a court may set aside a domestic contract, or part of it, if a party did not disclose significant assets, or significant debts or other liabilities, that existed when it was made; if a party did not understand its nature or consequences; or otherwise under the law of contract, for example where someone signed under pressure. A term in the contract cannot switch these grounds off (s. 56(7)).
So the work before the signing matters most:
- Exchange full financial disclosure: income, assets and debts, with documents.
- Get separate legal advice. The Act requires independent legal advice only for family arbitration agreements (s. 59.6(1)(b)), not for these contracts. It is still the usual answer to "did you understand what you signed?" Each partner sees their own lawyer, and many lawyers sign a certificate of independent legal advice attached to the agreement.
- Do not leave it to the week of the wedding. A contract presented days before the ceremony invites the argument that someone signed under pressure.
What a notary can and cannot do: A notary public checks each signer's government photo ID, watches each signature being made, and signs as the witness. A notary can also commission any affidavit or statutory declaration that goes with the agreement. A notary does not draft the agreement, review it for fairness, advise on property or support, or give independent legal advice. For those, each partner needs their own family lawyer.
How the Signing Works with Minute Notary
Why it is in person. Ontario lets wills and powers of attorney be witnessed over video under set conditions (Succession Law Reform Act s. 4; Substitute Decisions Act s. 3.1), and lets affidavits and statutory declarations be commissioned remotely (O. Reg. 431/20). The Family Law Act has no such provision for domestic contracts, so we witness cohabitation agreements and marriage contracts in person, on a mobile visit: the notary comes to your home, office or another place that suits you (contact us to confirm your area). The notary signs as the witness. The signing is part of our notarizing signatures service.
- Finish the agreement first. Both of you have had legal advice and agree on the final version. Print it and leave every signature line blank. We can bring printing at $0.40 per page (black and white).
- Get in touch. Contact us or call (613) 434-5555. Tell us whether you will sign together or separately, and how many signed originals you need.
- On the visit: each signer shows valid government photo ID and signs (and initials, if your lawyer asked for it) while the notary watches, and the notary signs as the witness.
- After the visit: each of you keeps a signed original. If you sign at separate appointments, the second visit is a second trip.
Other Paperwork Around Living Together or Marrying
These are sworn documents, not contracts, so they can be commissioned online by video:
- A statutory declaration of common-law union, when an employer, insurer, pension plan or bank asks you to confirm that you live together. Start from our statutory declaration of common-law union template.
- IRCC's IMM 5409, for a common-law sponsorship. See our IMM 5409 guide.
- Form 26B, if you ever file the agreement with the court so its support terms can be enforced as if they were a court order (s. 35). See Form 26B and Form 6B, sworn online.
Pricing
| Service | Fee | Note |
|---|---|---|
| Witnessing a cohabitation agreement or marriage contract (mobile visit) | $24.95 per seal + $60 travel fee (up to 30 km from our nearest office in Ottawa or Toronto), once per trip | Plus HST and card processing |
| Statutory declaration of common-law union (online) | $24.95 per stamp | Plus HST and card processing |
| Form 26B affidavit for filing a domestic contract with the court (online) | $24.95 per stamp | Plus HST and card processing |
| Printing on request | $0.40 per page | Black and white |
Note: the first signer is included; if more than one person signs the same document, each additional signer is charged an additional-signer fee of $24.95. The travel fee covers up to 30 km from our nearest office in Ottawa or Toronto; beyond that, an additional travel fee applies.
All fees are shown in full before you pay. See every posted rate on our pricing page.
Frequently Asked Questions
Does a cohabitation agreement need to be notarized in Ontario?
No. Section 55(1) of the Family Law Act makes a domestic contract, including a cohabitation agreement or a marriage contract, unenforceable unless it is made in writing, signed by the parties and witnessed. It does not require a notary. Many couples still sign in front of one because a neutral witness who checks photo ID makes the signing easier to prove later.
Who can witness a cohabitation agreement or marriage contract in Ontario?
The Family Law Act says the contract must be witnessed, but it does not say who the witness must be or how many witnesses there must be. In practice, choose an adult who is not a party to the agreement and has nothing to gain from it; a notary public is one option. Follow the witness lines in your agreement, and if your lawyer drafted it with a particular signing arrangement, use that. The notary can be the witness.
What is the difference between a cohabitation agreement and a prenup?
A cohabitation agreement is for two people who live together, or plan to, and are not married to each other (s. 53). A prenup is what most people call a marriage contract, which is for two people who intend to marry or are already married to each other (s. 52). Both must be in writing, signed and witnessed. If the partners to a cohabitation agreement marry each other, it is deemed to be a marriage contract (s. 53(2)).
Can you get a prenup after marriage in Ontario?
Yes. Section 52(1) of the Family Law Act lets two people who are married to each other, or who intend to marry, make a marriage contract. A contract signed after the wedding, sometimes called a postnup, is still a marriage contract and follows the same rules: in writing, signed by both spouses and witnessed.
Can a cohabitation agreement or marriage contract be signed online in Ontario?
Ontario's rules for witnessing over video cover wills and powers of attorney, and the Family Law Act has no equivalent, so Minute Notary witnesses cohabitation agreements and marriage contracts in person, on a mobile visit. Sworn documents around them, such as a statutory declaration of common-law union, can be commissioned online.
Do we both have to sign at the same time?
Section 55(1) does not require it. Each partner can sign at a separate appointment, as long as each signature is witnessed. Tell us when you get in touch whether you will sign together or separately, so we can plan one visit or two.
Is independent legal advice required for a cohabitation agreement or marriage contract?
The Act does not require it, but a court can set aside a domestic contract if a party did not understand its nature or consequences, or if significant assets, debts or other liabilities were not disclosed (s. 56(4)). Separate legal advice for each partner, plus full financial disclosure, is the usual way to protect the agreement. A notary cannot give that advice.
How much does it cost to have a cohabitation agreement or marriage contract witnessed?
On a mobile visit, the posted rate is $24.95 per seal plus a $60 travel fee once per trip (up to 30 km from our nearest office in Ottawa or Toronto; beyond that, an additional travel fee applies), plus HST and card processing. The first signer is included; each additional signer on the same document is charged an additional-signer fee of $24.95. Lawyers' fees are separate.
Final Recommendation
Pick the right contract: a cohabitation agreement if you live together without marrying, a marriage contract if you are engaged or married. Do the hard part, full disclosure and separate legal advice, well before any wedding date. Then sign it properly: in writing, both signatures, each watched by a neutral witness. A notary on a mobile visit gives you that witness with an ID check on record.
Book Your Appointment
Need your cohabitation agreement or marriage contract witnessed? Minute Notary witnesses domestic contracts on a mobile visit and commissions the sworn declarations around them online.
- Contact us: Ask a question or request a visit
- Call: (613) 434-5555
- Service page: Mobile notary
- Free template: Cohabitation agreement
- Related guide: Separation agreement in Ontario: how to sign and witness it
- Hours: Every day, Saturday and Sunday included, 8:00 AM to 8:00 PM (Ottawa time)
Sources
- Family Law Act, R.S.O. 1990, c. F.3 (Ontario), ss. 1, 2(10), 4(2), 5, 19, 21, 29, 33(4), 35, 51–56, 59.6
- Succession Law Reform Act (Ontario), s. 4
- Substitute Decisions Act, 1992 (Ontario), s. 3.1
- O. Reg. 431/20: Administering Oath or Declaration Remotely (Ontario)
- Ontario Court Forms: Family Law Rules forms (Form 26B, Affidavit for Filing Domestic Contract with Court)
This article was written using AI.
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About the author
Kai Mai
Co-founder & Chief Technology Officer, Minute Notary
Kai Mai writes and edits the Minute Notary guides, working from the published federal and Ontario guidance each article links, and from what Ottawa clients actually run into with certified copies, affidavits, statutory declarations, travel consent letters, and immigration paperwork. These guides are general information written by our editorial team — not legal advice, and not a professional opinion on your document. The receiving authority always has the final say.