CRAのサイト
https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/rental-income/renting-below-fair-market-value.html
> You do not report this amount in your income, and you cannot claim rental expenses. This is a cost-sharing arrangement, so you cannot claim a rental loss.
> If you lose money because you rent a property to a person you know for less money than you would to a person you don't know, you cannot claim a rental loss.
> When your rental expenses are consistently more than your rental income, you may not be allowed to claim a rental loss because your rental operation is not considered to be a source of income.
> You can claim a rental loss if you are renting the property to a relative for the same rate as you would charge other tenants and you expect to make a profit.
この説明だと、いくらで貸すかによるみたい。市場価格より安かったり、家賃収入が投資物件維持のコストより低い場合は、家賃収入として申告しなくて良い。同時に投資物件のメンテや税金やモーゲージ利息などを経費としてクレーム出来ない。