The home office deduction, under Canadian rules
Search this and most of what comes back is American. The rules that actually govern your claim are CRA's, they are written for Form T2125, and two of the three things that matter most — the either/or test and the carry-forward — are stated wrongly on nearly every page that ranks for it in Canada.
You qualify if you meet either one of two conditions, not both. Either the space is your principal place of business, or you use it only to earn business income and you use it on a regular and ongoing basis to meet clients, customers or patients. Meeting one is enough.
Your claim cannot be more than your net income from the business before you deduct these expenses, so it can never create or increase a loss. Anything you cannot use this year carries forward to the next fiscal period and can be claimed against that year's business income.
This page covers business-use-of-home expenses for self-employed people reporting on Form T2125. The rules for employees claiming home office costs against employment income are a different regime with different tests, and nothing below applies to them.
The test is "either", not "both"
Here is CRA's wording on business-use-of-home expenses, reduced to its structure. You can deduct expenses for the business use of a workspace in your home as long as you meet one of these conditions:
- it is your principal place of business; or
- you use the space only to earn your business income, and you use it on a regular and ongoing basis to meet your clients, customers or patients.
That "or" does a great deal of work, and a startling number of Canadian pages replace it with "and". Under the wrong reading, a consultant who works from a spare room and never has a client set foot in the house does not qualify — which would disqualify a large share of the self-employed population. Under the actual rule, that consultant meets the first condition on its own and is done.
Why the two conditions are structured this way. The second condition exists to let people claim a space that is not their principal place of business — a therapist's treatment room in a house where the main practice is elsewhere, for example. It carries the stricter "only to earn business income" requirement precisely because it is the more generous door. If your home is where the business actually runs from, you are already through the first door and the exclusivity requirement in the second is not yours to meet.
What you can claim on the business-use portion
You do not deduct these costs in full. You deduct the business-use share of them, worked out on a reasonable basis. CRA lists the following as deductible in that proportion:
- Heat
- Home insurance
- Electricity
- Cleaning materials
- Property taxes
- Mortgage interest — the interest only, never the principal portion of the payment
- Capital cost allowance, with the significant caveat set out further down this page
Note what is not on that list: the principal portion of your mortgage payment, and the purchase price of the house itself. If you rent rather than own, check CRA's business-use-of-home page for how the list applies to a rented home before you build the claim.
Working out your business-use portion
CRA asks for a reasonable basis. In practice that means area, time, or both together.
By area
Take the square footage of the workspace and divide it by the total finished area of the home. A 200 square foot room in a 2,000 square foot house is 10%. Measure it once, write down how you got there, and keep the note — the number itself is rarely the thing an auditor questions, but an unexplained percentage is.
By time
If the space does double duty — a dining table, a corner of a living room — area alone overstates the claim, because the room is not a workspace for the other sixteen hours of the day. Apportion by time as well. A table used ten hours a day, five days a week, is in business use for 50 of the week's 168 hours, or about 30% of the time.
Where both apply, multiply them. A dining area that is 10% of the home's floor space and in business use 30% of the time gives a business-use portion of 3%.
A worked example, including the cap
Round numbers, chosen to make the arithmetic visible. A sole proprietor owns a 2,000 square foot home and uses a dedicated 200 square foot room as the only place the business operates from — 10% by area, and no time adjustment because the room is not used for anything else.
| Cost | Annual total | 10% business use |
|---|---|---|
| Heat | $2,000 | $200 |
| Electricity | $1,200 | $120 |
| Home insurance | $1,500 | $150 |
| Cleaning materials | $300 | $30 |
| Property taxes | $5,000 | $500 |
| Mortgage interest | $10,000 | $1,000 |
| Total | $20,000 | $2,000 |
So the calculated business-use-of-home expense for the year is $2,000. Now the cap bites.
Suppose this was a slow year and the business's net income, after every other deduction but before business-use-of-home expenses, was $1,200. The deduction cannot be more than that figure. So:
- Claimed this year: $1,200, taking net income to nil.
- Carried forward to the next fiscal period: $800.
The $800 is not lost. It becomes available against business income in the next fiscal period, subject to the same cap in that year. This is the part almost nobody explains, and it is the reason to calculate the full amount every year even when you already know the business will not absorb it — a number you never worked out is a number you cannot carry forward.
For contrast, take the same house but a dining-table workspace at 3% business use. The calculated expense is $600, comfortably under the $1,200 income cap, so the whole amount is deductible this year and nothing carries forward.
Source: CRA, Business-use-of-home expenses, CRA page updated 2026-08-31. Dollar figures in the example above are illustrative only.
Capital cost allowance on your home: read this before you claim it
Capital cost allowance is on the list of deductible items, and claiming it can have consequences when you sell your home. The principal residence exemption is what normally keeps the gain on your home out of tax. Claiming CCA on the business portion of a home can affect how that exemption applies to that portion when the property is sold, which means a deduction worth a few hundred dollars a year can interact with a much larger number later.
This is an accountant's question, not a bookkeeper's, and it depends on facts about your property and your plans that no web page knows. Ask before you claim CCA on your home — not in the year you sell.
Everything else on the list — heat, insurance, electricity, cleaning materials, property taxes, mortgage interest — carries no equivalent trap. The caution is specific to CCA.
What to keep, and for how long
The claim is only as good as the records behind it. Keep the utility and insurance bills, the property tax notices, the mortgage statement showing the interest portion, and the measurement note explaining how you arrived at your percentage. CRA's general rule is six years from the end of the last tax year the records relate to, so the file you build this year has to survive a while.
Two habits make this painless. Have the bills land in one place all year rather than being reconstructed each spring, and record the business-use percentage in writing the first time you calculate it so it does not quietly drift by three points a year. The wider month-by-month version of that discipline is on the monthly bookkeeping checklist, and if you are assembling all of this for someone else to file, what your accountant actually needs from you at year-end lists the rest of the package.
Stop rebuilding a year of utility bills every spring
We keep your home office costs, percentages and supporting documents captured as the year goes, so your claim is calculated on evidence you can hand over in a folder rather than an estimate you defend from memory.
If you are not sure your books can support any of your deductions right now, the twelve signs your books are wrong is the faster diagnostic.
Questions people actually ask
Do I have to meet both CRA conditions to claim a home office?
No. It is an either/or test. You qualify if the workspace is your principal place of business, or if you use the space only to earn business income and use it on a regular and ongoing basis to meet clients, customers or patients. Meeting one condition is enough. A great many Canadian pages state this as a two-part test, which would wrongly disqualify most people who work from a spare room.
Can the home office deduction create a business loss?
No. Your business-use-of-home deduction cannot be more than your net income from the business before you deduct these expenses, so at most it takes your business income to nil. It can never push you into a loss or make an existing loss bigger. If your calculated amount is larger than that year's income, the excess is not lost — it carries forward to the next fiscal period.
What happens to the part of the home office deduction I cannot use?
It carries forward to the next fiscal period and can be deducted against business income in that year, subject to the same income cap again. This is the reason to calculate the full amount every single year even when you already know the business cannot absorb it. An amount you never worked out is an amount you cannot carry forward, and there is no way to reconstruct it later without the bills.
What home expenses can a self-employed Canadian actually deduct?
The business-use portion of heat, home insurance, electricity, cleaning materials, property taxes, mortgage interest and capital cost allowance. You cannot deduct the principal portion of a mortgage payment, and you cannot deduct the cost of the house itself. Everything is claimed as a proportion, never in full.
How do I calculate the business-use percentage of my home?
On a reasonable basis, which usually means area, time, or both. Divide the workspace square footage by the total finished area of the home for the area percentage. If the space also gets personal use, work out the fraction of the week it is in business use and multiply the two together. A 200 square foot room in a 2,000 square foot home is 10% by area; if that space is only in business use about 30% of the time, the business-use portion is 3%. Write down how you arrived at the number and keep it with the bills.
Should I claim capital cost allowance on my home?
Ask an accountant before you do. Capital cost allowance is on CRA's list of deductible business-use-of-home costs, but claiming it on your home can affect how the principal residence exemption applies to the business portion when you eventually sell. That trade-off depends on your property, how long you expect to own it and what the business portion looks like — none of which a general page can assess. The other costs on the list carry no equivalent complication.