为了严谨一些,找到cra的guide.
Cra是这样说的,
Renting below fair market value
You can deduct your expenses only if you incur them to earn income. In certain cases, you may ask your son or daughter, or another relative living with you, to pay a small amount for the upkeep of your house or to cover the cost of groceries. You do not report this amount in your income, and you cannot claim rental expenses.
This is, in fact, a cost-sharing arrangement, so you cannot claim a rental loss.
If you lose money because you are renting a property to a relative for a lower rate than you would rent it to other tenants, 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. However,
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 reasonably expect to make a profit.
在这个guide的第十六页。
http://www.cra-arc.gc.ca/E/pub/tg/t4036/t4036-12e.pdf