Common-Law Tax Rules
When you become common-law for CRA, what changes, how to tell CRA and the mistakes that lead to benefit repayments.
The short version
- For tax, you're common-law with someone you live with in a conjugal relationship once any of these is true: you've lived together for 12 continuous months, you have a child together (by birth or adoption), or your partner has custody and control of your child and the child depends on them for support.
- Separations of less than 90 days don't break the 12 months.
- From then on, CRA treats you exactly like a married couple: combined income for benefits, shared credits, one principal residence, attribution rules.
- Tell CRA by the end of the month after the month you became common-law (the 12-month mark, or the birth or adoption). Not telling CRA doesn't change your status, it just means benefits get clawed back later.
- Tax status and family law are different. Being common-law for CRA doesn't give you the property rights of a married spouse under every provincial law.
Common-Law Tax Rules in Canada
CRA doesn't care whether there was a ring, a cake or a dad-joke speech. It cares whether you live together in a conjugal relationship, and for how long. On the day the clock hits 12 months, you're a couple for tax, whether or not either of you noticed. Most problems with common-law status come from one person updating CRA and the other not, or from benefits continuing at the single rate for a year after the move-in. Here's how to get it right.
When You Become Common-Law
| Situation | Common-law for tax? |
|---|---|
| Living together 8 months, no children | No, not yet |
| Living together 12 continuous months | Yes, from the 12-month mark |
| Living together 12 months, with a 2-month separation in the middle | Yes; a breakup of less than 90 days doesn't break the period |
| Living together 3 months and you have a baby together | Yes, from the birth (or adoption) |
| Living together, your partner has custody of your child who depends on them | Yes |
| Roommates, no conjugal relationship | No |
CRA looks at the substance: shared home, shared finances, how you present yourselves to others, and the relationship itself. A separate lease or separate bank accounts don't decide it.
Are you common-law for tax?
Tell the assistant when you moved in, any breaks, and whether you have children together. It tells you whether and from when you're common-law for CRA, and what changes for your benefits and credits.
What Changes
- Benefits: the Canada child benefit and the Canada Groceries and Essentials Benefit are based on your combined family income from the month after you become common-law; see Canada child benefit.
- Single-parent credits: the eligible dependant amount is generally lost; the spouse amount may apply if your partner's income is low; see spouse amount.
- Sharing: pooled medical expenses and donations, transfers of unused credits, pension income splitting and spousal RRSPs all become available.
- One principal residence: if you each own a home, only one can be designated per year from the year you become common-law; see principal residence exemption.
- Attribution: income from money you give or lend your partner to invest can be taxed back to you.
- First-time buyer programs: your partner's home ownership can affect your eligibility; see Home Buyers' Plan and FHSA.
The full list, with an example of the benefit change, is on marriage and taxes; the tax rules are the same for common-law partners.
Telling CRA
- Work out the date you became common-law: the 12-month anniversary of moving in, or the birth or adoption of your child.
- Update your status in My Account (or on form RC65) by the end of the following month. Each of you should update your own account.
- Expect a recalculation of benefits from the following month, and a notice showing the new amounts.
- Each of you reports the other's net income on your returns from then on.
If you're late, CRA recalculates back to the date you actually became common-law and asks for the overpaid benefits back. CRA also runs reviews of marital status, often by asking for leases, utility bills and bank statements; see CRA review letter.
Common Mistakes
- Counting from the wedding-like moment instead of the move-in date.
- Only one partner updating CRA, so the two returns disagree.
- Staying "single" for the Canada child benefit after a year together. That's the most common reason for a large benefit repayment.
- Assuming two homes keep two exemptions once you're common-law.
- Confusing tax and family law. In some provinces, including Ontario, common-law partners don't automatically share property the way married spouses do on a breakup. That's a family law question, not a tax one.
When a Common-Law Relationship Ends
After 90 days apart because of the breakdown, you're separated for tax, from the first day apart. Support, property and benefits then follow the same rules as married couples; see separation and divorce. Other life changes are on life events and taxes.
Common-Law Tax Questions
When are you considered common-law in Canada for taxes?
When you live in a conjugal relationship with someone and have lived together for 12 continuous months, or you have a child together by birth or adoption, or your partner has custody and control of your child who depends on them for support.
Does a short breakup reset the 12 months?
No. Separations of less than 90 days do not break the 12-month period.
Do common-law couples file taxes together?
No. Each partner files their own return, but each reports the other’s net income, and benefits are based on combined family income.
When do I have to tell CRA I am common-law?
By the end of the month after the month you became common-law. Benefits are recalculated from the following month.
Are the tax rules different for common-law and married couples?
For federal income tax purposes, they are the same. Family law rights on a breakup can be different, depending on the province.
Sources: CRA, Definitions (common-law partner, separation); Has your marital status changed?. Checked October 2026. The custody-and-control part of the definition and the factors CRA weighs are summarized from the Income Tax Act definition of common-law partner and CRA's guidance as we understand them. Provincial family law is not covered; Quebec is not covered.
Last reviewed October 5, 2026 against CRA and Government of Canada sources. How we check our facts.