Many Canadians do not realize they have become common-law for tax purposes until a benefit changes or the CRA asks questions. The tax definition of common-law is not based on whether you call each other spouses. It depends on the CRA’s tests.
The basic CRA test
You are usually common-law for tax purposes if either of these is true:
| Test | Rule |
|---|---|
| 12-month rule | You have lived together in a conjugal relationship for 12 continuous months |
| Child rule | You share a child by birth or adoption, or one partner has custody and the other supports the child |
If you meet either test, CRA expects you to report common-law status.
What counts as living together?
Living together does not mean you are physically under the same roof every night without exception. Temporary absences usually do not break the count.
Examples that often do not reset the 12-month period:
- work travel
- short-term schooling elsewhere
- visiting family
- temporary medical or family-related absences
What is a conjugal relationship?
CRA looks at the relationship as a whole.
Common indicators include:
- shared home or routine living arrangement
- shared finances or household responsibilities
- presenting yourselves socially as a couple
- emotional and economic interdependence
Why this matters for taxes and benefits
Once CRA treats you as common-law, certain benefits and credits are recalculated using combined family income.
| Program | Effect |
|---|---|
| GST/HST credit | Based on combined income |
| Canada Child Benefit | Based on combined family income |
| Spousal amount | May become relevant |
| Medical and donation claims | Pooling options may improve tax result |
That is why some people see benefits drop after becoming common-law.
Common situations people ask about
| Situation | Likely Tax Answer |
|---|---|
| Living together 8 months, no child | Usually not common-law yet |
| Living together 12+ months | Usually yes |
| Have a child together after 4 months | Often yes sooner |
| Keep separate bank accounts | Can still be common-law |
| One partner travels often for work | Still may be common-law |
What if you do not update CRA?
That can cause problems.
You may face:
- benefit overpayments
- reassessments
- repayment demands
- possible interest charges
The issue is usually not that CRA is looking for a label. It is that the wrong marital status changes benefit calculations.
Common-law for tax vs provincial family law
Tax treatment and family-law rights are not always the same.
| Topic | Tax Rules | Family Property Rules |
|---|---|---|
| Common-law definition | Federal CRA rules | Provincial law varies |
| Property division on breakup | Not a CRA issue | Depends on province |
If you want the broader legal and financial picture, see common-law relationships in Canada.
Bottom line
You are likely common-law for tax purposes if you have lived together in a conjugal relationship for 12 continuous months or you meet the child-related rule sooner. Once that happens, CRA expects your marital status to be updated, and your benefits and tax calculations may change.