The \"Five-Year Rule\" for Common-Law Property Rights in Ontario: Fact or Myth?

Many people believe that once an unmarried couple in Ontario has lived together for five years, they automatically become entitled to split property the way divorcing spouses do. It’s one of the most repeated pieces of family law folklore in the province — and it’s wrong. There is no length of cohabitation, five years or otherwise, that turns a common-law relationship into a marriage for property purposes.

The confusion matters because it changes how people plan — or fail to plan — their financial lives together. Believing in a five year rule for common-law property rights in Ontario can leave you badly exposed if the relationship ends and most of the assets are held in your partner’s name.

This guide explains where the myth comes from, what Ontario law actually provides for common-law partners, and what you can do instead of relying on a rule that doesn’t exist.

Where the Myth Comes From

Cohabitation length does matter somewhere in Ontario family law — just not for property.

Under the Family Law Act, an unmarried partner can qualify as a "spouse" for spousal support purposes if the couple cohabited continuously for a minimum period set out in the Act, or if they are in a relationship of some permanence and are parents of a child together. That support-eligibility threshold is the likely real source of the "five-year rule" story — it has simply been misremembered and applied to the wrong question.

Meeting the support definition of "spouse" opens the door to a possible support claim. On its own, it does not create any ownership interest in your partner’s house, pension, investments, or business.

What Ontario Law Actually Says About Common-Law Property

This is the part that surprises people: common-law partners in Ontario have no automatic right to equalization of property under the Family Law Act, no matter how long they lived together — one year or twenty-five.

Equalization — the process that shares the growth in a married couple’s net worth roughly equally — is a right reserved for married spouses. If you were never married, that statutory sharing regime simply does not extend to you, regardless of how integrated your finances became.

In practice, that generally means:

• Property stays with whoever holds legal title or made the purchase
• There’s no statutory "matrimonial home" protection for a home owned solely by one common-law partner
• A long relationship, shared bills, and even shared children don’t, by themselves, create ownership

So Is a Long-Term Common-Law Partner Left with Nothing?

Not necessarily — but any claim has to come from somewhere other than a length-of-time rule.

Two related legal routes exist for common-law partners who contributed money, labour, or both to a partner’s property or to a shared life together:

1. An unjust enrichment or trust claim — arguing your partner was unfairly enriched at your expense, with no legal justification, because of what you contributed
2. A joint family venture claim — used where a couple genuinely pooled effort and resources toward common family goals over a long-term relationship, potentially allowing a share of the accumulated wealth rather than repayment for specific tasks

These are fact-driven claims. They depend on evidence of what each partner actually contributed and how the relationship functioned financially — not on a cohabitation anniversary.

Married vs. Common-Law: What Actually Differs

How to Protect Yourself, Instead of Relying on a Myth

If you’re in a common-law relationship, the most reliable protection isn’t a length-of-time rule — it’s a plan.

• [ ] Consider a cohabitation agreement setting out how property will be handled if you separate (valid under the Family Law Act when it’s in writing, signed by both partners, and witnessed)
• [ ] Keep records of financial contributions to major purchases, renovations, or a shared home
• [ ] Discuss and document how significant assets — a house, a business, an inheritance — are meant to be owned and shared
• [ ] Revisit the agreement if your relationship or finances change significantly

Frequently asked questions