Marriage Contracts and Common Law Relationships: What You Need to Know in Ontario
                     Marriage Contracts and Common 
Law Relationships: What You Need 
to Know in Ontario
BTL Law Firm
January, 2026
SparationAgreementOntario.ca Page 1
Contents
Understanding Marriage Contracts in Ontario ........................................................................................ 2
How Common Law Relationships Are Treated Differently in Ontario ................................................... 3
Can Common Law Couples Use “Marriage Contracts” in Ontario? ....................................................... 4
What Issues Common Law Couples Can Address in a Contract ............................................................. 5
Key Legal Requirements for Enforceable Agreements in Ontario .......................................................... 7
Benefits of Having a Contract in Marriage and Common Law Relationships ......................................... 
8
Limitations of Marriage Contracts and Cohabitation Agreements in Ontario ....................................... 
10
When Couples Should Update Their Agreement .................................................................................. 11
When to Seek Legal Advice in Ontario................................................................................................. 12
Contact us today!.................................................................................................................................. 13
Understanding Marriage Contracts in Ontario
Marriage contracts in Ontario often called prenuptial agreements (before 
marriage) or postnuptial agreements (after marriage) are legally 
recognised under the Family Law Act. These contracts allow couples to 
outline their financial rights and responsibilities both during the 
relationship and if the relationship ends. For many Ontarians, they 
provide clarity, transparency, and long-term financial protection.
Couples choose to create a marriage contract at different stages of their 
relationship. Some prepare a contract before getting married to address 
expectations early, while others wait until after marriage to formalise 
financial arrangements once their life circumstances become clearer.
Unlike informal promises, a properly drafted marriage contract becomes 
a legally enforceable document once both partners sign with full 
financial disclosure and independent legal advice.
A well-designed marriage contract can cover a wide range of issues. 
Most commonly, Ontario couples use these agreements to set out how 
property will be divided, including assets such as real estate, 
investments, or business interests. They may also include terms related
to spousal support, outlining whether support will be paid and under 
what conditions. In some cases, marriage contracts address estate rights, 
helping clarify what each spouse is entitled to upon death and ensuring 
the agreement aligns with estate planning documents.
Marriage contracts have become increasingly popular in Ontario for 
several reasons. Rising home values, blended families, and personal or 
business assets that people want to protect have encouraged more 
couples to consider formal agreements. Many also view marriage 
contracts as a practical planning tool much like insurance that can 
prevent conflict and uncertainty later. By clearly setting expectations 
from the start, these agreements offer peace of mind and help couples 
build their future on a foundation of openness and mutual understanding.
How Common Law Relationships Are Treated 
Differently in Ontario
Common law relationships in Ontario are treated very differently from 
legally married spouses, especially when it comes to property rights and 
financial entitlements. Under Ontario law, common law spouses are 
couples who have lived together in a conjugal relationship for at least 
three years, or for any length of time if they share a child by birth or 
adoption. This definition is important because certain rights especially 
related to support only arise once a couple meets this threshold.
One of the biggest distinctions between married and common law 
couples in Ontario is how the law views their property. Married spouses 
are entitled to equalisation of net family property under the Family Law 
Act, meaning they share the increase in value of their assets accumulated 
during the marriage. Common law partners, however, do not have 
automatic property rights or equalisation, regardless of how long they 
lived together. If a common law partner believes they have contributed 
to a property owned by the other spouse, they must make a claim based 
on trust law such as unjust enrichment or resulting trust to seek
compensation. This requires proving contributions that increased the 
asset’s value, which can be complex without a written agreement.
Support obligations, on the other hand, can apply to both married and 
common law spouses. Under Ontario law, common law partners may be 
entitled to spousal support if they meet the definition of spouses under 
the Family Law Act or the Divorce Act (for parenting-related matters). 
Courts examine factors such as financial need, the length of the 
relationship, contributions to the household, and economic disadvantage 
resulting from the relationship. However, because there is no automatic 
entitlement, support claims often rely on detailed financial and factual 
evidence to prove that support is appropriate.
Because of these significant differences, many common law couples in 
Ontario choose to create cohabitation agreements a form of domestic 
contract similar to a marriage contract to clarify property ownership, 
financial responsibilities, and support expectations. Without one, 
common law partners may face uncertainty or costly legal disputes if the 
relationship ends.
Can Common Law Couples Use “Marriage 
Contracts” in Ontario?
In Ontario, common law couples cannot technically use a marriage 
contract because that term applies only to legally married spouses or 
those planning to marry under the Family Law Act. Instead, common 
law partners use a similar type of domestic contract called a cohabitation 
agreement. While the terminology is different, the purpose and legal 
effect of the agreement are very similar.
A cohabitation agreement allows common law partners to set out their 
financial rights and responsibilities both during the relationship and if it 
ends. These agreements serve the same core purpose as marriage 
contracts: they help partners protect assets, clarify expectations, and 
reduce the risk of disputes. For common law couples who do not have
automatic property rights or equalisation under Ontario law a 
cohabitation agreement can be even more important because it provides 
certainty that the legislation does not automatically offer.
Timing is flexible for these agreements. Common law partners can 
create a cohabitation agreement before moving in together, which is 
often ideal because it ensures that financial expectations are clear from 
the start. However, couples can also enter into one after they have 
already begun living together, or even after they have lived together for 
many years. If a couple decides to marry later, the cohabitation 
agreement can automatically become a marriage contract, provided the 
terms still reflect both partners' wishes.
In terms of legal rights, a cohabitation agreement can address many of 
the same issues covered in a marriage contract. Partners can outline how 
property will be owned, how expenses will be shared, what happens to 
assets if the relationship ends, and whether spousal support will be paid. 
While cohabitation agreements cannot override certain rights related to 
children, they can provide strong protection and clarity for adults in the 
relationship. For common law couples in Ontario, these agreements offer 
a level of security similar to what married couples receive through a 
marriage contract making them a valuable tool for planning and 
protecting the future.
What Issues Common Law Couples Can Address in 
a Contract
Common law couples in Ontario can use a cohabitation agreement to 
address many of the same financial and property-related issues that 
married couples include in a marriage contract. Because common law 
partners do not benefit from automatic property rights or equalisation 
under the Family Law Act, a written agreement is often the strongest 
way to create clarity and protect both partners’ interests.
One of the most important topics common law couples can cover is 
property ownership and how assets will be divided if the relationship 
ends. This includes real estate, vehicles, bank accounts, business 
interests, and any assets acquired during the relationship. Without a 
contract, common law partners must rely on complex trust-based claims 
to divide property, so documenting ownership and division in writing 
helps avoid costly disputes.
A cohabitation agreement can also protect partners from unjust 
enrichment claims, which are common when one partner contributes 
financially or through labour to property owned by the other. By clearly 
stating who owns what, how contributions are treated, and what 
compensation if any would apply after separation, partners can 
significantly reduce legal uncertainty.
Spousal support is another key issue. Common law couples can use the 
agreement to set spousal support expectations, whether that means 
outlining how support will be calculated, setting conditions for support, 
or agreeing to waive spousal support entirely (provided it is done fairly 
and with proper legal advice). These terms give partners predictability 
and help align expectations from the start.
Cohabitation agreements can also outline responsibilities for shared 
expenses, such as rent or mortgage payments, utilities, groceries, and 
upkeep of the home. Clarifying financial responsibilities helps prevent 
misunderstandings and ensures each partner knows their contributions to 
the household.
Finally, common law partners can address how gifts, inheritances, and 
debts will be treated during the relationship and upon separation. For 
example, the agreement may specify that inheritances remain each
partner’s separate property, or that each person remains responsible for 
their own pre-existing debts. Establishing these rules in writing ensures 
fairness and prevents disputes during emotionally difficult times.
Overall, a cohabitation agreement gives common law couples in Ontario 
a practical, proactive way to protect their financial future and outline 
clear expectations for the relationship.
Key Legal Requirements for Enforceable 
Agreements in Ontario
For a marriage contract or cohabitation agreement to be enforceable in 
Ontario, it must meet several important legal requirements under the 
Family Law Act and Ontario case law. Courts take these requirements 
seriously because domestic contracts have long-term financial 
consequences. Ensuring the agreement is prepared properly helps protect 
both partners and increases the likelihood that the terms will be upheld if 
ever challenged.
A foundational requirement is full financial disclosure from both 
partners. Each person must provide accurate and complete information 
about their income, assets, debts, liabilities, and anything else relevant to 
the agreement. Without proper disclosure, the agreement may be set 
aside later because one partner could argue they did not understand the 
true financial picture when entering into the contract.
Another key requirement is independent legal advice (ILA). While not 
technically mandatory in every case, Ontario courts strongly expect both 
partners to obtain their own legal advice. Lawyers explain rights, 
obligations, and the consequences of signing the agreement. If one or 
both partners did not receive ILA, a court may question whether the 
agreement was truly informed, or whether one party failed to appreciate 
what they were giving up.
The agreement must also be voluntary and free from pressure. Any signs 
of coercion, manipulation, or rushing such as presenting the contract 
immediately before a wedding or move-in date can make the agreement
vulnerable to being set aside. Both partners must have enough time to 
review, negotiate, and understand the terms without emotional or 
financial pressure.
Ontario law also requires proper signing and witnessing. The contract 
must be in writing, signed by both partners, and witnessed by someone 
who is not a party to the agreement. Keeping well-organised records 
including copies of the agreement, disclosure documents, and 
certificates of independent legal advice is essential if the agreement is 
ever reviewed by a court.
Finally, courts assess fairness and validity based on the circumstances at 
the time the agreement was created and the circumstances at the time of 
enforcement. Courts look for signs of imbalance, lack of understanding, 
inadequate disclosure, or terms that are shockingly one-sided. Even if an 
agreement technically meets the formal requirements, a court may still 
modify or set aside parts of it if enforcing the contract would produce an 
unfair or unconscionable result.
Benefits of Having a Contract in Marriage and 
Common Law Relationships
Whether a couple is legally married or living in a common law 
relationship, having a formal agreement either a marriage contract or a 
cohabitation agreement offers significant legal and financial benefits in 
Ontario. These agreements act as proactive planning tools that help 
couples protect what matters most and establish clear expectations 
before issues arise.
One of the strongest advantages is protecting personal and family assets. 
This includes property owned before the relationship, inheritances, 
family cottages, business shares, or investments contributed by relatives. 
By documenting what belongs to each partner and how assets will be 
treated in the event of separation or death, couples can safeguard
property that might otherwise be subject to dispute or complex legal 
claims.
A well-drafted agreement also helps reduce conflict during a separation. 
Instead of navigating stressful disagreements about money, property, or 
support, partners can rely on clear, predetermined terms. This reduces 
the emotional burden of separation and can significantly lower legal 
costs. In many cases, couples who have a contract experience a faster, 
smoother separation because major decisions were already addressed 
when both partners were cooperative and thinking clearly.
These contracts also play a key role in clarifying expectations before 
cohabitation or marriage. Discussing financial values, responsibilities, 
ownership, and future plans encourages transparency early in the
relationship. Couples who understand each other’s expectations about 
money, support, and property are better equipped to build trust and avoid
misunderstandings.
For individuals with entrepreneurial or professional interests, a contract 
is invaluable in preserving business assets, investments, or pensions.
Without clear terms, a separation can pose risks to corporate shares, 
partnerships, intellectual property, or retirement funds. A domestic
contract can specify that the business remains separate property, 
ensuring continuity and preventing disruptions.
Finally, these agreements support long-term financial planning. By 
outlining how expenses will be shared, what happens to property over 
time, and how financial responsibilities will evolve, couples can make 
informed decisions about saving, investing, and planning for the future. 
A contract provides a roadmap that helps both partners feel secure and 
aligned as they move forward together.
Overall, marriage contracts and cohabitation agreements offer Ontario 
couples peace of mind, greater financial stability, and a clear framework 
for both day-to-day living and long-term life changes.
Limitations of Marriage Contracts and Cohabitation 
Agreements in Ontario
While marriage contracts and cohabitation agreements are powerful 
tools for financial planning and relationship clarity, they do have legal 
limitations in Ontario. Understanding these boundaries helps couples 
draft agreements that are realistic, enforceable, and aligned with the 
Family Law Act and the best interests of any children involved.
One important limitation is that certain clauses will not be enforced by 
Ontario courts, even if both partners agreed to them. For example, any 
attempt to restrict or eliminate child support is invalid. Child support is 
considered a right that belongs to the child, not the parents, and cannot 
be negotiated away in a private contract. Courts will also ignore terms 
that contradict Federal Child Support Guidelines or prevent a child from 
receiving appropriate financial support.
Domestic contracts also have limited power when it comes to parenting 
decision-making and mobility. Couples cannot use a marriage contract 
or cohabitation agreement to predetermine custody arrangements, 
restrict future mobility (such as preventing a parent from moving), or 
dictate decision-making authority. Courts will always base parenting 
orders on the best interests of the child, which can change over time.
Any clause attempting to lock in future parenting outcomes is unlikely to 
be upheld.
Another significant limitation arises from incomplete or inaccurate 
financial disclosure. If one partner withholds information about income, 
assets, debts, or financial obligations, the agreement becomes vulnerable 
to being set aside. Courts have repeatedly ruled that full disclosure is a 
fundamental requirement; without it, the disadvantaged partner could not 
have made an informed decision. This means that failure to disclose 
even unintentionally creates real legal risk.
Even well-drafted agreements may need updating because major life 
changes can affect their fairness and enforceability. Events such as 
having children, receiving a large inheritance, starting a business, 
retirement, illness, or significant changes in income may require the 
contract to be reviewed and revised. Courts are more likely to question 
agreements that no longer reflect the couple’s reality or produce unfair 
outcomes when circumstances shift dramatically.
Overall, while domestic contracts offer strong protection and clarity, 
they are not absolute. Understanding their limitations ensures that 
Ontario couples create agreements that are both legally sound and 
adaptable to the natural changes that occur throughout a long-term 
relationship.
When Couples Should Update Their Agreement
Marriage contracts and cohabitation agreements are most effective when 
they reflect a couple’s current financial and personal circumstances. As 
relationships evolve, major life events can make an existing agreement 
outdated or incomplete. In Ontario, couples are encouraged to review 
and update their domestic contract whenever their situation changes in a 
meaningful way, ensuring the agreement continues to offer clarity, 
protection, and fairness.
A common time to update an agreement is when a couple marries after 
previously signing a cohabitation agreement. Although most 
cohabitation agreements automatically convert into marriage contracts 
upon marriage, the original terms may no longer reflect the couple’s 
expectations or financial situation. Updating the agreement at this stage 
ensures it accurately addresses new priorities, obligations, and long-term 
plans.
Another important milestone is the birth or adoption of children. Having 
children introduces new financial responsibilities, parenting 
considerations, and long-term needs. While domestic contracts cannot 
predetermine parenting arrangements or child support, they may include
updated financial planning, estate considerations, or spousal support 
expectations that reflect the realities of parenting.
Couples should also revise their agreement when there are significant 
changes in income, assets, or debt. This includes major promotions, job 
loss, inheritances, substantial savings growth, or increased debt loads.
Changes in financial capacity can impact support obligations, asset 
protection strategies, and the fairness assessment courts may apply if the 
contract is ever challenged.
Another key moment to revisit an agreement is when partners purchase a 
home together or start a business. These major investments introduce 
shared ownership, liability risks, and long-term financial commitments. 
Updating the agreement helps clarify each partner’s contributions, 
ownership shares, and expectations if the relationship ends or the 
business evolves.
Finally, couples should consider reviewing their agreement during a 
relationship breakdown or reconciliation. If partners separate 
temporarily and later reconcile, an updated contract can reaffirm 
expectations and address issues that may have caused conflict. Similarly, 
during a breakdown, revisiting the contract with legal advice ensures 
both partners understand their rights and responsibilities as they move 
forward.
By proactively updating their agreement at these key moments, couples 
ensure that their marriage contract or cohabitation agreement remains 
relevant, fair, and legally strong throughout the relationship.
When to Seek Legal Advice in Ontario
Seeking legal advice is an essential step for couples creating or updating 
a marriage contract or cohabitation agreement in Ontario. Because these 
agreements carry long-term financial and legal consequences, consulting 
with an Ontario family lawyer helps ensure the contract is fair, 
enforceable, and fully compliant with the Family Law Act.
Legal advice is especially important to confirm that the agreement meets 
all statutory requirements. Lawyers ensure the contract is drafted in 
accordance with Ontario law, properly signed and witnessed, and based 
on complete financial disclosure from both partners. Without these 
elements, the agreement may be vulnerable to challenges in court, 
reducing the protection it was meant to provide.
Independent legal advice is also crucial for understanding the long-term 
consequences of spousal support waivers or limitations. Choosing to 
waive support can have serious impacts later, particularly if one partner 
experiences financial hardship, takes on more child-rearing 
responsibilities, or becomes unable to work due to illness or disability. A 
lawyer can explain how support rights work in Ontario and help clients 
make informed decisions about what is fair and reasonable in their 
circumstances.
Legal guidance can also help couples avoid clauses that courts are likely 
to invalidate. Terms that attempt to restrict child support, predetermine 
parenting arrangements, or impose penalties for future behaviour (such 
as relationship rules) are routinely struck down by Ontario courts. A 
lawyer can identify problematic terms and ensure the agreement focuses 
on enforceable financial and property matters.
Contact us today!
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