A self-employed taxpayer can claim a business portion of home expenses based on the percentage of the home used for business purposes.
The percentage claimed of all the allowable expenses is normally based on a square footage basis. The business taxpayer can include mortgage interest and taxes along with the other operating costs in the calculation.
It appears that around 8-12% of the home expenses end up being claimed.
Note, that you should not claim depreciation (capital cost allowance) in your calculation, since its inclusion could result in a portion of the capital gain on the disposition of your principal residence being taxes.
Also, keep in mind, that an employee cannot include mortgage interest or taxes in the total cost for allocation.
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