Thanks for your question. You are considered to be in a common-law relationship if you have lived together with your partner for more than 12 consecutive months, or if you have a child together, either related to you by blood or through adoption, or if you have primary custody of a child under the age of 18.
The 12-month cohabitation period must be complete by Dec. 31 of the year of filing. Under Canadian law, same sex couples and couples of the opposite sex are both treated the same for income tax purposes. Please click here for more information.