What These Agreements Generally Are
A marriage contract and a cohabitation agreement are both types of what Ontario family law generally calls a "domestic contract" — a written agreement between two partners that sets out how they want certain things handled, rather than leaving everything to the default rules that would otherwise apply. In broad terms, a marriage contract is generally made by two people who are married or planning to marry, while a cohabitation agreement is generally made by two people who are living together, or planning to live together, without being married.
This page gives a general side-by-side introduction to both. It intentionally stays at a high level — for a deeper, more detailed look at either type of agreement on its own, see our in-depth guides to marriage contracts and cohabitation agreements. If you are weighing whether you need a lawyer at all for a separation-related document, our guide on whether you need a lawyer to separate may also be useful background.
How They Are Similar
In practice, marriage contracts and cohabitation agreements are often built the same way and tend to serve a similar general purpose: giving a couple more certainty and control over financial questions than they might otherwise have. Both are generally written documents, signed by both partners, and both generally work best when each person has had a genuine opportunity to understand what they are agreeing to before signing.
Both types of agreement typically focus on financial matters — property, debt, and support — rather than on arrangements for children. Parenting time, decision-making responsibility, and child support are usually addressed separately, since courts generally retain the ability to look at a child's best interests at the time those issues actually arise. See our guide on parenting agreements for how arrangements for children are typically approached.
Both also generally rely on the same two safeguards to hold up well later: honest, financial disclosure from each partner, and independent legal advice for each person, rather than one shared lawyer or an informal understanding between the couple.
How They Differ
The clearest difference is simply who the agreement is generally for: a marriage contract involves spouses who are married or about to marry, while a cohabitation agreement involves partners who are not married. That distinction matters because married spouses and unmarried, common-law partners are not treated identically under Ontario's default family property rules, so the "starting point" that each type of agreement is generally adjusting can look a little different.
Another point worth knowing generally: if a couple has a cohabitation agreement and later marries, Ontario family law generally treats that agreement as continuing to operate, in effect as a marriage contract, unless the agreement itself says otherwise. This is one reason many people choose to revisit a cohabitation agreement with their own lawyer if their relationship later changes, such as through marriage, rather than assuming nothing needs a second look.
Beyond that, the two documents tend to be quite similar in form and in the kinds of financial topics they generally address, which is why this page treats them together rather than as entirely separate subjects.
Marriage Contracts vs. Cohabitation Agreements at a Glance
The table below is a general, simplified comparison. It is meant to orient you, not to answer how either type of agreement would apply to your own situation.
| Feature | Marriage Contract | Cohabitation Agreement |
|---|---|---|
| Who it is generally for | Spouses who are married or planning to marry | Partners who are living together, or planning to, without marrying |
| What it can generally address | Property, debt, spousal support, and related financial matters | Property, debt, and support between the partners, on a generally similar basis |
| Children's parenting or child support | Generally not treated as final or binding in the same way | Generally not treated as final or binding in the same way |
| If the couple later marries | Not applicable — already a marriage contract | Generally continues to apply, in effect as a marriage contract, unless it says otherwise |
| Independent legal advice | Widely recommended for each person before signing | Widely recommended for each person before signing |
Why Couples Consider One
Deciding whether to put a marriage contract or cohabitation agreement in place is a personal choice, and there is no single "typical" reason. Some couples are drawn to the general idea of clarity — knowing in advance, in broad terms, how certain financial questions would be handled if the relationship later ended, rather than leaving it to default rules or a difficult conversation down the road.
Others consider one because they are bringing a business, a home they owned before the relationship, savings, or an inheritance into the relationship and want to think through how that might generally be treated. Blended families — where one or both partners have children from a previous relationship — sometimes use these agreements to help clarify financial expectations, separate from the parenting arrangements those children have with their own parents. None of these reasons is required, and plenty of couples choose not to sign anything at all; it depends entirely on what a given couple wants certainty around.
What These Agreements Typically Address
Generally speaking, marriage contracts and cohabitation agreements tend to focus on financial topics such as how property and debt will be divided or kept separate, how a shared home might be treated, whether spousal support will be paid and on what general basis, and how gifts, inheritances, or pre-relationship savings will be handled. See our guides on financial disclosure and separation agreements for related context on how financial questions are generally approached once a relationship actually ends.
These agreements typically do not finally decide parenting time, decision-making responsibility, or child support, since those questions are usually assessed based on the child's circumstances and best interests at the relevant time, rather than fixed years in advance. If children are part of the picture, a separate conversation about parenting agreements is usually more appropriate.
Steps Many Couples Take to Put One in Place
There is no single required process, but many couples follow a broadly similar general pattern when putting a marriage contract or cohabitation agreement together.
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Talk openly about goals and concerns
Many couples start with a plain conversation about what each person hopes the agreement will and will not do, before any drafting begins.
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Each person arranges their own independent legal advice
One lawyer generally cannot advise both partners. See Independent Legal Advice for what this typically involves.
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Exchange full and honest financial disclosure
Each partner generally shares a genuine picture of their income, assets, and debts. See Financial Disclosure for a general overview.
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Draft the agreement based on what was actually discussed
The document should generally reflect what both people understood and agreed to, not a template neither person reviewed carefully.
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Review the draft privately with your own lawyer
This is generally the point at which each person's lawyer explains, in plain terms, what the agreement would generally mean for them specifically.
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Sign, have it witnessed, and keep copies
Both partners generally keep a signed copy, along with any financial disclosure exchanged, in case the agreement needs to be referred to later.
Why Independent Legal Advice Matters
It can be tempting, especially early in a relationship, to treat a marriage contract or cohabitation agreement as a quick formality — something to sign and move past. In reality, these are significant financial documents that can be difficult to unwind later, so the way they are put together generally matters as much as what they say.
Do not sign a marriage contract or cohabitation agreement without your own independent legal advice. Agreements reached without each person getting their own lawyer's advice, or without full and honest financial disclosure, are generally at greater risk of being challenged or set aside later. Getting independent advice before you sign — not after — is widely considered the safer approach, and something many family law professionals recommend without exception.
Independent legal advice generally means each partner meets, on their own, with their own lawyer, who explains the general effect of the agreement, answers questions, and confirms the person understood what they were signing. See Independent Legal Advice for a fuller, general explanation of what this usually involves and why it is treated as important.
Changing or Challenging an Agreement Later
Circumstances change, and many couples eventually revisit a marriage contract or cohabitation agreement — for example, after having children, buying property together, or a significant change in either partner's finances. Generally, an existing agreement can be updated later if both partners agree in writing to the change. See Changing an Agreement for a general explanation of how this typically works.
In some situations, a person may later question whether an agreement should be enforced at all — for instance, if financial disclosure was incomplete, if one person did not get independent legal advice, or if the circumstances around signing were otherwise unfair. See Challenging an Agreement for a general look at how these situations are typically approached. Because outcomes depend heavily on the specific facts, this is an area where individualized legal advice is particularly useful.
Frequently Asked Questions
What is the difference between a marriage contract and a cohabitation agreement?
Both are written agreements between partners about how money, property, and support will generally be handled, but a marriage contract is generally made by spouses who are married or planning to marry, while a cohabitation agreement is generally made by partners who are living together, or planning to, without marrying. In practice they often cover similar ground and are drafted in a similar way.
Do we need one of these agreements if we don't have much property?
Not necessarily. These agreements are a personal choice rather than a requirement, and plenty of couples never sign one. They tend to feel more useful when there is a business, a home, savings, debt, or a blended family to think through, but the decision ultimately depends on what each couple wants clarity around.
If we have a cohabitation agreement and later marry, does it still apply?
Often, yes. Ontario family law generally treats a cohabitation agreement as continuing to apply, in effect as a marriage contract, once a couple marries, unless the agreement itself says otherwise. Because this can have real consequences, it is worth discussing directly with your own lawyer when the agreement is drafted, or reviewing again if you later marry. See How They Differ above.
Can a marriage contract or cohabitation agreement decide child support or parenting arrangements?
Generally, no, not in a binding, final way. Courts generally remain able to look at what is in a child's best interests at the time, regardless of what a contract says, so provisions about parenting time, decision-making, or child support are typically treated differently from provisions about property or spousal support.
Does each person need their own lawyer to sign one of these agreements?
It is not always a strict legal requirement, but it is widely considered good practice, and in many cases it materially affects how reliable the agreement turns out to be later. One lawyer generally cannot advise both partners, since their interests are not the same, so independent legal advice for each person is the general recommendation. See Why Independent Legal Advice Matters above.
Can we write our own agreement without lawyers?
People sometimes draft an initial version together to capture what they have discussed, but having each person's own lawyer review, advise on, and often finalize the document is generally recommended before signing, especially for anything meant to be relied on later.
Can a marriage contract or cohabitation agreement be challenged later?
Yes, in some circumstances. Issues such as incomplete financial disclosure, one person not having independent legal advice, or unfairness in how the agreement was reached can affect whether it holds up later. See our guide on challenging an agreement for a general explanation.