It is March 1st of 2021 and Mark and Carice, Canadian Citizen of Ontario, have come to you asking for your assistant to clarify and explain their 2020 income tax returns. They are a married couple and have three children: Maxim, Yola, and John aged 15, 12, and 8 years respectively. Mark (51) works full-time for a Canadian scientific underwater research and development corporation (his employer) located in Kingston, Ontario. Mark has worked for this corporation of to the Kingston office for 9 years. Mark earned a net come for tax purposes of 85,000 in 2020. His employer withholds maximum CPP contributions and EI premiums. Carice (45) worked part-time for a convenience store in Kingston From January 2020 to Feb 2020. She earned a new income for tax purposes of 3,525 in 2020. All of the children are in good health and none of them have an income of their own. Mark and Carice came up to you to discuss the following tax matters.

1) Mark said "In addition to our family home located in Kingston, Ontario, we, as a couple, own a cottage located in Muskoka District Muncipality, Ontario, which we usually visit in the summer. We are considering selling both real estate properties next year (2021) and moving to the USA". The cottage cost $320,000 and has a current market value of $520,000. Their family home originally cost $300,000 and is now valued at $600,000. The couple has owned the cottage for five years and the home for ten years. Carice said" I heard that if a property qualifies as a principal residence, we can use the principal residence exemption to reduce or eliminate any capital gain otherwise occurring, for income tax purposes, on the disposition of the property. So if, we sell our home and cottage, how do we know which one (home or cottage) is the principal residence?". Mark raised his hand and said "How we could calculate the number of years that each property would be designated as the principal residence if we were to sell both homes this year.