If you rent out one or more rooms in your home, or if you own a rental property, there are many expenses that can be deducted in calculating your net rental income. These expenses include mortgage interest (but not principal), property taxes, utility costs, house insurance, maintenance costs, advertising, and property management fees.If I'm not mistaken you can only claim the interest portion of the mortgage payment not the entire payment. Since it is only a room you are renting out you should talk to an accountant to find out what portion of the mortgage interest you are allowed. I do not believe it is half. Do check into other deductions you might be eligible to make besides mortgage interest: such as a portion of repairs, utilities, strata fees, taxes etc.