The definition of who is and who is not a spouse, both for legal
and income tax purposes, has changed a lot in the last few decades.
Some previously discriminatory laws have been abolished (for
example, the bar to same-sex couples marrying) and some rules have
been updated to reflect societal norms (for example, a common law
spouse is considered a spouse under the Income Tax Act
(Canada)).
Unfortunately, there continues to be inconsistency in the law on
who is considered a spouse. For example, a person will be
considered a common law spouse (or partner) after just one year of
cohabitation under the Income Tax Act. However, under the
Ontario Family Law Act, a person will be considered a
common law spouse only after three years of cohabitation, unless
the partners have a child together earlier. Also, different
provinces and territories define a common law spouse (or partner or
domestic partner) in different ways. Some require certain steps to
be taken, for example Nova
