Introduction
Home office expenses are one of the most commonly claimed deductions by incorporated professionals — and one of the most frequently challenged by the CRA. The rules for deducting a home office through a corporation differ from the employment home office deduction, and many professionals apply the rules incorrectly — claiming deductions that are either too large or not properly structured.
Scenario: The CRA Questions Dr. Isabeau's Home Office Claim
Dr. Isabeau is a dermatologist in Toronto who operates through a professional corporation. Her MPC claimed $18,000 in home office expenses across 2023 and 2024 — representing a portion of her mortgage interest, property taxes, utilities, and maintenance, allocated based on her home office occupying 20% of the total square footage.
The CRA's desk review requests documentation of the home office claim, including:
• A description of the dedicated workspace
• A floor plan or description of the home's square footage
• Evidence that the space is used exclusively for work
• Calculation methodology for the percentage claimed
The Corporate Home Office Rule
For expenses to be deductible through the corporation, the corporation must be paying rent to the shareholder-employee for the use of a home office — or the expenses must flow through an employment arrangement where the corporation requires the home office use and reimburses the shareholder-employee's home expenses.
Unlike a sole proprietor who can deduct a portion of actual home expenses directly on a T2125, a corporation cannot directly deduct home expenses it does not actually incur. The proper structure is:
The corporation pays the shareholder-employee a reasonable rent for the use of the home office, or the shareholder-employee incurs the expenses and the corporation reimburses them under an employment arrangement (with a T2200 or equivalent documentation of the employment requirement).
The shareholder-employee who receives rent from the corporation for the home office must report that rent as personal income — partially offset by the home expenses they can deduct. The net personal income position and the corporate deduction should be properly documented and consistent.
What "Exclusive Use" Actually Means
The CRA's longstanding position is that the home office must be used exclusively for work — not just primarily, but exclusively. A guest room that doubles as a home office does not qualify. A kitchen table where work is also done does not qualify. A dedicated room used solely for professional work — and from which personal activities are excluded — qualifies.
For Dr. Isabeau, the 20% square footage claim is plausible for a house with a dedicated consultation room or medical records room. But if the CRA's review determines that the claimed space is a room that also serves personal functions — a den that has a desk — the exclusivity requirement is not met.
Supporting the Claim
A defensible home office claim is supported by:
A clear description of the dedicated workspace (room dimensions, location in the home)
Evidence that it is used exclusively for professional activities
A reasonable calculation of the square footage percentage
Documentation of the corporate rent arrangement or employment reimbursement structure
Copies of the expense receipts (mortgage interest certificate, property tax bill, utility invoices)
The Outcome for Dr. Isabeau
If the workspace meets the exclusivity test and the calculation is reasonable, the claim survives the review. If the auditor determines the space is not exclusively used for work, the deduction is denied — and the $18,000 is added back to corporate income, generating approximately $2,196 in additional corporate tax plus interest.
In practice, many home office claims are partially successful — the auditor accepts the principle of the deduction but requires a lower percentage, or accepts the claim for the T2 but questions the corporate rental arrangement structure.
When to Speak With a CPA
Before claiming a home office deduction through a corporation, the structure of the claim should be reviewed with a CPA. The rent arrangement between the shareholder and the corporation must be documented, the exclusive-use test must be met, and the calculation must be supportable with receipts.