If a couple before to get married each own a house and designated each of them primary residence and they sell one of the residence the year that they get married, can they get the full primary residence tax gain excemption for that property? Otherwise how does it work?
Yes, only the person who sells their home will report the sale and claim the Principal Residence Exemption on their tax return.
For the taxation years before the year of marriage and including the year of marriage, both individuals would be able to claim their respective residences as their principal residence. However, in the taxation years after the year of marriage, the two individuals would be spouses throughout the year and therefore, only one property may be designated as their principal residence for a particular year. To get the full Principal Residence Exemption and fully shelter both properties from tax, they'll have to sell one no later than the tax year in which they get married.