More Ontarians are choosing to live together without getting married and recent data clearly reflects this shift. As of 2021, 15.7% of couples in Ontario were in a common-law relationship. This represents a gradual but steady rise over time. Growth has been especially notable among two groups: younger adults entering their first committed relationships and older adults who are forming new partnerships after separation, divorce, or death of a partner.
Common law unions are widespread among people aged 20 to 24 and common-law couples with children are more likely to be stepfamilies, often blending children from prior relationships.
Although Ontario’s 2025 statistics have not yet been released, all indicators point toward continued growth. As more couples choose this arrangement, it becomes increasingly important to understand the legal framework governing common-law relationships, especially because the rights of common-law partners in Ontario are very different from the rights of married spouses.
Despite their popularity, common-law relationships do not automatically trigger the same legal protections as marriage, particularly in the areas of property division, rights to the home and inheritance. As an Ontario family lawyer, I regularly meet people who are surprised to learn that long-term cohabitation alone does not provide the protections they assumed. Without proper planning or legal understanding, these assumptions can lead to serious financial consequences.
This article offers a clear overview of how Ontario law treats common-law partners, how property and support claims work, how Ontario differs from provinces like British Columbia and why the recent Ontario Court of Appeal decision in Mullin v. Sherlock (2025 ONCA 510) is an important example of how courts evaluate long-term common-law relationships.
1. When Are You Considered Common-Law in Ontario?
The term “spouse” is used differently across various Ontario statutes. For common-law couples, the relevant definition comes from Section 29 of the Family Law Act, found in Part III – Support Obligations.
Under Section 29, you are considered a spouse for support purposes if:
- You have lived together continuously for at least 3 years, or
- You have a child together and have lived in a relationship of some permanence.
This definition is limited. It applies to support claims such as spousal support and child support, but it does not extend to:
- Property division
- Rights to the home
- Equalization
- Inheritance rights
The CRA uses a different definition for tax purposes and considers you common-law after 12 months of living together. This has no impact on your Ontario family-law rights.
2. Common-Law vs. Married Spouses: Why the Distinction Matters
One of the most significant differences in Ontario family law is how married and common-law spouses are treated when their relationship ends.
Married spouses have statutory property-sharing rights. Under the Family Law Act, married spouses are presumptively entitled to share in the growth of each other’s property during the marriage through the equalization process. While the court still applies the statutory formula, the law starts from the assumption that married spouses share property accumulated during the marriage unless an exception applies.
Common-law spouses do not have equalization rights. Regardless of how long they live together, common-law partners do not automatically share property, do not have special rights to the home and do not inherit if their partner dies without a will.
3. Property Rights for Common-Law Partners in Ontario
In Ontario:
-Property belongs to whoever’s name is on title
-Common-law partners do not automatically share assets
-There is no equalization process for common-law couples
-A partner must prove legal entitlement through unjust enrichment or a related claim
3.1 Unjust Enrichment in Simple Terms
To succeed with an unjust enrichment claim, a partner must prove:
1. The other partner was enriched. Examples include:
- Receiving financial support
- Benefiting from unpaid labour
- Gaining career or business advantages because the other partner handled domestic responsibilities
2. The claimant suffered a deprivation. Examples include:
- Contributing money to assets not in their name
- Losing career opportunities
- Providing unpaid work to a business
3. There was no legal justification. Meaning:
- It wasn’t a gift
- It wasn’t a contract
- There was no other valid reason to explain the enrichment
If all three elements are met, the court agrees it would be unfair for the enriched partner to retain all the benefits.
3.2 Joint Family Venture (JFV)
Courts may find a Joint Family Venture when the couple functions like a long-term financial and domestic team. Factors include:
a) Mutual effort - Did both partners contribute to shared goals?
b) Economic integration - Did they share finances, expenses, or financial planning?
c) Intent to build a life together - Did their behaviour show an intention to build a financial future together?
Prioritizing the family’s needs - Did one partner make personal or career sacrifices for the household?
This concept was central in the 2025 Ontario Court of Appeal case of Mullin v. Sherlock, where the couple lived together for over 12 years and Ms. Mullin contributed significantly to the Mr. Sherlock’s business. The Court of Appeal found a Joint Family Venture and confirmed she was entitled to 50% of the increase in the business’s value.
3.3 Remedies for Unjust Enrichment
If unjust enrichment is established, the court chooses the remedy.
A. Monetary award (most common)
This may compensate for:
- The value of unpaid labour
- A share of wealth created during the relationship (the value-survived method)
B. Constructive trust (less common)
This gives the claimant an ownership interest in a specific asset, such as part of the home.
It is only used when:
- Money is insufficient and
- The contribution relates directly to the property
Most cases result in monetary compensation rather than property ownership.
4. Case Example: Mullin v. Sherlock (2025 ONCA 510)
The Ontario Court of Appeal’s decision in Mullin v. Sherlock is a clear illustration of how courts treat long-term common-law relationships.
Background
The couple lived together for over 12 years before marrying briefly. During cohabitation, Ms. Mullin contributed significantly to both the household and Mr. Sherlock’s business. The business increased substantially in value during this period.
Key Findings
The evidence showed:
- The couple operated as a financial and domestic team
- Ms. Mullin provided unpaid labour
- Her contributions directly supported business growth
- Both partners viewed the business as connected to their shared future
Court’s Decision
The Court of Appeal confirmed that:
- Unjust enrichment was made out
- A Joint Family Venture existed
- A monetary award was the appropriate remedy
- Ms. Mullin was entitled to 50% of the increase in the business’s value
Why It Matters
The case demonstrates that three important points:
i) Marriage is not required for significant compensation
ii) Long-term cohabitation and substantial contributions matter
iii) Courts look beyond legal title to the economic reality
5. Spousal Support for Common-Law Partners
A common-law partner may claim spousal support if:
- The couple lived together for 3 or more years, or
- They share a child and lived together in a committed relationship.
Support may be awarded when one partner sacrificed career or income, supported the other’s business, or faces economic hardship after separation.
6. Parenting and Child Support
For parenting issues, marital status does not matter. Parents share parenting time, decision-making responsibility and child support obligations. Child support is mandatory under the Federal Child Support Guidelines.
7. Estate Rights
If a person dies without a will, a common-law partner does not inherit automatically. Married spouses inherit under intestacy law. Common-law partners must be protected through:
- A will
- Updated beneficiary designations
- Updated RRSP/RRIF and pension designations
- Powers of Attorney
8. Practical Checklists
Before or During Cohabitation:
- Discuss financial expectations
- Clarify ownership of major assets
- Keep records of contributions
- Sign a cohabitation agreement
- Update wills and beneficiaries
If You Are Not on Title:
- Keep proof of mortgage or bill payments
- Track renovation contributions
- Document unpaid domestic or business work
- Use written agreements
During Separation:
- Seek legal advice early
- Gather financial documentation
- Assess unjust enrichment and JFV claims
- Address support issues
- Negotiate a separation agreement
- Consider mediation or court
9. Ontario vs. British Columbia
Ontario’s laws differ significantly from British Columbia’s. In BC:
- Common-law begins after 2 years
- Property and debt are divided 50/50
- Title does not matter
- The family home is shared
Ontario does not automatically divide property for common-law partners. A partner must prove unjust enrichment or a related claim.
10. Common Misunderstandings
- Living together does not make you married
- You do not get half the house unless you prove it
- Common-law partners do not inherit automatically
- Property is not divided unless legal tests are met
11. Summary
Common-law couples in Ontario do not have the same rights as married spouses. Married spouses benefit from the equalization system, while common-law partners must prove unjust enrichment or a Joint Family Venture to receive compensation.
As common-law relationships continue to grow, it is increasingly important for couples to understand the legal realities. Planning ahead, documenting contributions, signing cohabitation agreements and preparing wills can protect both partners and prevent financial hardship.
