How does the home office deduction work in Canada?

The two ways to qualify

A home workspace is deductible for a business owner if it meets one of two tests:

• It is your principal place of business, or
• It is used exclusively for business and used on a regular and continuous basis to meet clients or customers

Most self-employed people who run their business from home meet the first test easily. The second test matters for those who also have another office but use a dedicated home space to see clients. A spare room used occasionally for admin, while your real base is elsewhere, generally does not qualify.

Calculating the business proportion

You deduct the business share of your home costs, usually calculated by area: the square footage of the workspace divided by the total finished area of the home. A 150-square-foot office in a 1,500-square-foot home is 10%.

If the space doubles as personal space part of the time, you further prorate by the hours of business use. A dining room used as an office during business hours is claimed at the area percentage multiplied by the business-hours percentage. A genuinely dedicated office needs no time adjustment.

What you can include

Apply your business percentage to the running costs of the home:

• Heat, electricity and water
• Home insurance
• Maintenance and minor repairs
• Rent, if you rent, or mortgage interest (not principal) if you own
• Property taxes

Renters often come out ahead here, because the full business share of rent is deductible while owners can only claim the interest portion of the mortgage, not the principal repayment.

Why owners should be careful with CCA

Homeowners can claim capital cost allowance on the business portion of the home itself, but they generally should not. Claiming CCA on your home can jeopardise the principal residence exemption, which normally shelters the entire gain on your home from tax when you sell.

Trading a modest annual CCA deduction for partial exposure to capital gains tax on your home is almost always a bad deal. The standard advice is to claim the running costs but leave CCA on the home alone.

The loss restriction and carryforward

The home office deduction cannot create or increase a loss from your business. If your workspace costs exceed your net income before the deduction, you can only claim enough to bring income to nil.

The good news is that the unused portion is not lost: it carries forward indefinitely and can be claimed against business income in a future year, subject to the same restriction. So in a low-income year the deduction is banked rather than wasted.