When I first started working from my spare bedroom, I thought I could just write off half my rent. Ouch! It turns out the CRA is much more specific than that. To claim business-use-of-home expenses, that space needs to be your principal place of business or used exclusively for earning income and meeting clients. I had to measure my desk area versus the total finished square footage of my apartment. It’s a bit of a headache, but once you have that percentage, it changes everything!
You can deduct a portion of your heat, electricity, insurance, and even mortgage interest (though not the principal!). If you are renting, like I am, you can deduct the business portion of your rent. Imagine that! But remember, you can't use these deductions to create a business loss. If your business didn't make money this year, you have to carry those expenses forward to the next year.