Commercial leases in Canada come with a tax layer that catches many business owners off guard. A commercial lease in Ontario with a base rent of $3,000 per month attracts $390 in HST at 13%, bringing the total to $3,390 — and that’s before you factor in property taxes, maintenance, and insurance. The difference between what you expect to pay and what you actually owe can be substantial if you haven’t accounted for every tax component.
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This article is general information only and does not constitute professional advice. For your specific situation, consult a qualified professional.
Commercial lease taxes aren’t a single line item. They’re a collection of federal and provincial charges, operating cost pass-throughs, and registration thresholds that each work differently. Residential rent is HST-exempt in Canada, but commercial leases are fully taxable — and the rules around who pays what depend heavily on the lease structure you sign. Here’s what you actually need to know.
One term you’ll hear constantly in commercial leasing is TMI — Taxes, Maintenance, and Insurance.
What I tend to notice is that tenants focus on base rent and forget that TMI can add 30–50% or more to their monthly payment. A commercial lease’s hidden costs often outweigh the base rent difference between two properties.
How HST Applies to Commercial Leases in Canada
HST on commercial rent works differently from what most small business owners expect. Residential rent is exempt — no HST charged, no input tax credits available. Commercial rent is the opposite: fully taxable, and both landlord and tenant have specific obligations.
If you’re a landlord collecting commercial rent, you must register for HST once your taxable rental income exceeds $30,000 in a calendar year. That threshold includes short-term rental revenue too — anything under 30 consecutive days counts toward the $30,000 limit. Once registered, you calculate HST on each rent payment, collect it from the tenant, and remit it to the CRA on your regular GST/HST return.
For tenants, the picture is different. If you’re a GST/HST registrant yourself — meaning you charge HST on your own products or services — you can claim input tax credits on the HST you pay on commercial rent. That effectively reduces your net HST cost. If you’re not registered, the HST on your lease is a real expense you can’t recover.
Your lease agreement must be clear about whether the stated rent includes or excludes HST. A $3,000 monthly rent that’s “plus HST” means you pay $3,390 in Ontario. A rent that’s “including HST” means the landlord absorbs the tax — but that’s rare in commercial leases. Invoices from the landlord must show their business name and HST registration number. Without that number, you can’t claim your input tax credit.
Common Mistakes Tenants and Landlords Make With Commercial Lease Taxes
Mistaking TMI for a fixed cost
TMI isn’t a flat fee. It’s your proportionate share of the building’s actual operating costs, which change every year. A tenant in a 2,000-square-foot office in a 20,000-square-foot building pays 10% of the total TMI. If property taxes go up or maintenance costs rise, your TMI payment rises too. Landlords must provide an annual itemized TMI statement, typically 90–120 days after year-end. You usually have 30–60 days to object — miss that window and you’re stuck with the charges.
Ignoring the base year clause
Many commercial leases include a base year for TMI. You only pay increases in operating costs above that base year’s level. Sounds good — until you realise the base year expenses might be artificially low. A landlord could under-report expenses in the base year, making every subsequent year look like a big increase. Tenants should audit the base year expense report before signing. An audit typically costs $1,500–$5,000, but it can save you thousands annually if it catches inflated figures.
Not checking for gross-up clauses
A gross-up clause lets the landlord calculate variable operating costs as if the building were fully occupied, even when it isn’t. If the building is 70% occupied, the landlord can still report costs at 100% occupancy levels. Fixed costs like property taxes and insurance shouldn’t be grossed up — only variable costs like utilities and janitorial services. Read your lease’s gross-up language carefully. If it’s vague, expect higher TMI charges.
Assuming all commercial leases handle property taxes the same way
Property taxes in commercial leases depend entirely on the lease type. A gross lease means the landlord pays property taxes. A single net lease means the tenant pays rent plus a portion of property taxes. A double net lease adds insurance. A triple net lease puts everything — taxes, insurance, and maintenance — on the tenant. Sign a triple net lease without understanding it, and you’re effectively paying the building’s entire operating cost on top of your rent.
What You Need to Know About TMI Calculations and Lease Structures
How TMI is calculated
TMI starts with the building’s total operating costs for the year — property taxes, insurance, maintenance, utilities, janitorial, snow removal, and management fees. That total is divided by the building’s total rentable square footage to get a cost per square foot. Your share is that cost per square foot multiplied by your rentable area. Unusable spaces like elevator shafts and mechanical rooms are excluded from the total rentable area, so you’re not paying for space nobody uses.
Capital expenses — major structural improvements like a new roof or HVAC system — generally aren’t passed to tenants unless the lease specifically allows it. Routine maintenance is fair game. The distinction matters: a $50,000 roof replacement shouldn’t appear in your TMI statement, but a $500 gutter repair can.
TMI rates vary by property type and location
The range is wide. Downtown Toronto office space runs $18–$30+ per square foot in TMI. Suburban industrial space is $4–$8 per square foot. Retail falls in the middle at $10–$25 per square foot. A tenant leasing 1,000 square feet of downtown Toronto office space at $25 per square foot TMI pays $25,000 annually in operating costs alone — on top of base rent. That’s the kind of number that turns a seemingly affordable lease into an expensive one.
→ Scroll right to see all columns
| Property Type | TMI Range (per sq ft) | Typical Lease Structure |
|---|---|---|
| Downtown Toronto office | $18–$30+ | Triple net or modified gross |
| Suburban industrial | $4–$8 | Triple net |
| Retail | $10–$25 | Triple net or percentage lease |
Lease types and who pays property taxes
The lease type you sign determines your property tax exposure. A gross lease looks simple — one payment covers everything — but the landlord has built the tax cost into your rent. A triple net lease is transparent: you see exactly what you’re paying for taxes, but you also bear the full risk of tax increases. A percentage lease, common in retail, adds a base rent plus a percentage of your sales — property taxes are usually included in the base rent calculation but can shift if the lease is structured as triple net.
My first move would be to ask for a five-year TMI history before signing any lease. That shows you how much operating costs have risen and whether the building has any expensive surprises coming. A building with rapidly rising property taxes or frequent maintenance issues will cost you more every year.
Upcoming changes and what to watch for
Commercial property tax assessment methods are under review in several provinces. Ontario’s Assessment Act and British Columbia’s property tax system both face potential reforms that could shift how commercial properties are valued. Higher assessed values mean higher property taxes, which flow directly to tenants in triple net leases. Keep an eye on municipal budget announcements — a city facing a budget shortfall often raises commercial property tax rates faster than residential rates.
Frequently Asked Questions About Commercial Lease Taxes
Can I claim HST back on my commercial rent if I’m not registered for GST/HST? ▾
What happens if my landlord isn’t registered for HST? ▾
Is HST charged on the full TMI amount or just the base rent? ▾
Can I negotiate a lower TMI rate? ▾
What’s the difference between a gross-up clause and a base year clause? ▾
Do I need a lawyer to review my commercial lease’s tax provisions? ▾
Why Getting the Tax Structure Right Matters More Than the Base Rent
The base rent on a commercial lease gets all the attention, but the tax and operating cost structure determines what you actually pay over five or ten years. A lease with a low base rent and a high TMI can cost more than a lease with a higher base rent and a low, capped TMI. The difference compounds every year as property taxes rise and maintenance costs increase. If you’re comparing two spaces, run the numbers with TMI included — not just the base rent — and ask for a five-year projection of operating cost increases.
Remember: this article is general information only. For advice on your specific situation, speak to a qualified professional.
If this was useful, you might also want to read Must-Know Tips for Your Commercial Space Lease in Canada.
Sources and Further Reading
Tips for Navigating Variable Lease Rates in Canada — Understand how variable lease rates interact with tax obligations and operating cost pass-throughs.
CalculateHST.ca (2026). HST for Landlords and Property Owners in Canada. 🔗
Bomcas Commercial Real Estate (2025). Commercial Real Estate Taxation: Essential Guide for Canadian Businesses. 🔗
Commercial Real Estate Lawyer (2025). Property Taxes in Commercial Leases: Who Foots the Bill? 🔗
LawyerInfo.ca (2025). How to Calculate TMI (Taxes, Maintenance, and Insurance) on a Commercial Lease in Ontario. 🔗
