Hidden costs in Ontario commercial leases typically include TMI (Taxes, Maintenance, and Insurance), common area maintenance (CAM) charges, HVAC obligations, and rent escalation clauses. Unlike residential leases, Ontario's Commercial Tenancies Act does not cap operating costs or rent increases. What you pay depends almost entirely on what your lease says. Have a lawyer review it before you sign.
The rent figure on a commercial listing is rarely the full monthly cost. Many Ontario tenants sign a lease based on the quoted base rent only to be shocked when the first full invoice lands. The difference is almost always in the fine print, and the law offers far less protection to commercial tenants than most business owners assume.
This guide walks through the hidden costs most commonly buried in Ontario commercial leases, what to look for before signing, and what to negotiate so you are not carrying costs that should belong to the landlord.
Why Ontario Law Leaves the Hidden Costs to the Lease
Ontario's Commercial Tenancies Act, R.S.O. 1990, c. L.7 is the governing statute for commercial landlord-tenant relationships. Its most important feature, for our purposes, is what it does not do. The Act does not cap rent. It does not regulate operating costs. It does not limit how much a landlord can pass through to a tenant in additional rent.
As the Ontario government's own guidance on renting commercial property makes clear, a signed commercial lease agreement largely takes precedence over the Act. What the lease says is, for most practical purposes, what governs.
The consequence: there is no statutory safety net for commercial tenants. Due diligence before signing is not a "nice to have", it is the only real protection you have.
Understanding Gross vs. Net Leases in Ontario
Most hidden costs show up in net lease structures, so it helps to know what you are actually signing.
| Lease Type | What the Tenant Pays |
|---|---|
| Gross Lease | Fixed rent only; landlord pays taxes, insurance, and maintenance |
| Single Net (N) | Base rent plus property taxes |
| Double Net (NN) | Base rent plus property taxes and building insurance |
| Triple Net (NNN) | Base rent plus property taxes, building insurance, and maintenance |
A useful analogy: a gross lease is like renting a furnished condo where the landlord covers everything. A triple net lease is closer to renting a house where you also pay the property tax bill, the home insurance, and every repair that comes up.
Most Ontario commercial leases are some form of net lease. Triple net leases are especially common in retail and industrial spaces. Many leases blend gross and net elements, sometimes called a "modified gross" lease, and that is where language can get vague.
The danger is not the lease type itself. The danger is loose wording about what falls into "additional rent" and what does not.
TMI: The Cost That Can Double Your Rent
TMI, Taxes, Maintenance, and Insurance, is used almost interchangeably with "additional rent" in Ontario commercial leases. In a net lease, TMI is the line item where hidden costs pile up. It is not unusual for TMI to equal or exceed the base rent itself, effectively doubling your monthly cost.
Taxes
The "T" in TMI is your proportionate share of the building's municipal property taxes. In Ontario, commercial properties are assessed by the Municipal Property Assessment Corporation (MPAC) and typically taxed at higher rates than residential properties.
The risk is reassessment. When municipal property taxes rise, which they often do, the increase flows directly through to tenants in a net lease. Budget a meaningful portion of your base rent for property taxes, and ask the landlord for the historical tax figures for the past three years.
Maintenance
The "M" is where landlords have the most creative licence. Maintenance can cover the legitimate stuff: snow removal, landscaping, parking lot upkeep, elevator servicing, lobby cleaning, security, and general building repairs. These are reasonable pass-throughs to tenants.
The problem is that vague lease language lets landlords sneak capital expenditures into the maintenance line. A new roof, a full HVAC system replacement, or repaving the entire parking lot are not "maintenance" in any ordinary sense, they are capital improvements that benefit the landlord's asset for decades. If the lease is not explicit about excluding capital items, you could be billed for them.
HVAC is a particularly frequent battleground. In multi-tenant buildings, the HVAC system is often landlord-managed but charged back through TMI. How that charge is structured, and whether capital replacement is included, should be spelled out in writing.
Insurance
The "I" is the landlord's building and common-area liability insurance, paid by the landlord and recovered from tenants. It covers the building structure and shared spaces. It does not cover your business contents, your equipment, or your liability to customers, you must carry your own commercial insurance separately.
Red flags to watch for in the insurance line: the landlord charging their personal liability coverage, property-management employee benefits, or insurance on unrelated properties through your TMI. None of those belong on your invoice.
CAM Charges: The Fine Print That Matters Most
Common Area Maintenance (CAM) charges overlap heavily with the "M" in TMI. CAM covers shared building expenses, lobbies, parking lots, landscaping, exterior maintenance, and similar, and in multi-tenant buildings, costs are split based on your proportionate share of total building square footage.
The core problem with CAM is that there is no universal definition of what it includes. It varies from lease to lease, and Ontario law offers no cap.
Common CAM abuses to watch for:
- Double-billing. Charging a property management fee through CAM, then layering a percentage management fee on top. Some leases allow the landlord to charge for the property manager's salary and a 15% administrative surcharge on the same line.
- Capital improvements disguised as maintenance. Roof replacement and parking lot resurfacing are not maintenance. If your lease allows these in CAM, you may end up paying six-figure capital costs that should belong to the landlord.
- Vague catch-all language. Phrases like "any costs related to the property" or "any other expenses the landlord considers reasonable" effectively make CAM unlimited.
- Non-refundable reserve funds. Some landlords require tenants to pay into a "damage pool" or reserve fund that is non-refundable even if the tenant leaves.
What to negotiate:
- An annual cap on CAM increases (often tied to the Consumer Price Index).
- An explicit exclusion of capital expenditures from CAM.
- Audit rights, the right to review the landlord's expense records so you can verify what you are being charged for.
- Historical CAM data from the landlord for the past three years, before you sign.
HVAC, Structural Repairs, and Leasehold Improvements
Some of the most expensive hidden costs are not about monthly charges at all. They are one-time hits that can arrive with no warning.
HVAC
There is no default rule in Ontario that makes the landlord responsible for HVAC. Responsibility depends entirely on what the lease says. In triple net leases, HVAC maintenance and sometimes full replacement can fall to the tenant. Replacing a rooftop commercial unit is not cheap, and an unclear lease can leave you holding that bill.
What to negotiate: the split between repairs and replacement, and a dollar threshold above which responsibility shifts to the landlord. A clause that makes the landlord responsible for any single repair above a set dollar amount can protect you from one catastrophic bill.
Structural Repairs
Structural repairs, roof, foundation, load-bearing walls, exterior cladding, should generally be the landlord's responsibility. They are part of owning the building. But vague "tenant is responsible for all repairs" clauses can be interpreted broadly. A lease that says the tenant must handle "all repairs" could arguably include a significant roof repair.
Make sure the lease distinguishes structural repairs (landlord) from routine maintenance (tenant), and spells out who pays for major systems like the roof, foundation, and exterior walls.
Leasehold Improvements
If you are fitting out a retail space, a medical office, or a restaurant, you will likely spend significant money on improvements before you can open the doors. The lease should address two questions:
- Who owns the improvements at the end of the term? In many Ontario commercial leases, the landlord owns any fixed improvements, meaning you paid for upgrades that revert to the landlord when the lease ends.
- Are you required to restore the space to its original condition? Some leases require the tenant to remove all improvements and return the space to a "base building" condition. That can itself be a significant expense.
Negotiate a tenant improvement (TI) allowance, a contribution from the landlord toward your fit-out costs. Landlords often budget for this, and it is a normal part of commercial lease negotiation.
Rent Escalation and the Absence of Rent Control
Residential tenants in Ontario are used to seeing annual rent increase guidelines in the news. Commercial tenants have no equivalent protection. The Commercial Tenancies Act does not cap commercial rent increases. At all.
Within the term of a lease, rent usually escalates through a clause tied to a formula, the Consumer Price Index, a fixed percentage, or market rates. If that clause is vague, you face open-ended exposure. If it is specific and capped, you can plan.
At renewal, the situation is more stark. A landlord can propose any rent they want. Thirty percent, fifty percent, or more above your current rent is legally permissible. The landlord is under no obligation to renew at a similar rate. Your only leverage is whatever renewal terms you negotiated up front.
Best practice:
- Negotiate a clear, capped escalation formula during the lease term, for example, the lesser of 3% or CPI.
- Negotiate renewal options with predetermined rent figures or formulas, rather than leaving renewal rent to future negotiation.
Personal Guarantees: Your Home Is on the Line
Many commercial landlords require a personal guarantee from the business owner, especially for newer businesses or corporations without an established credit history. This is the single most important clause to understand in the entire lease.
A personal guarantee makes you personally liable for the rent if your business defaults. Your personal assets, your home, your savings, your investments, are on the line. Personal guarantees are ordinary contracts in Ontario, and the courts will enforce them.
If you are incorporated, a personal guarantee cuts through the corporate shield. The whole point of signing a lease through a corporation is to limit personal liability. A personal guarantee undoes that protection for the lease.
How to limit the risk:
- Burn-off clause. The guarantee expires after a period of timely rent payment, commonly two or three years.
- Dollar cap. The guarantee is capped at a fixed amount, such as six months' rent, rather than the full value of the lease.
- Limit to the initial term. The guarantee applies only to the initial lease term and does not automatically extend to renewals.
Whether a landlord will accept these modifications depends on the market, the strength of your business, and your negotiating leverage. But if you do not ask, the answer is always no.
Spotting Hidden Costs in Ontario Commercial Leases: A Pre-Signing Checklist
Before you sign any Ontario commercial lease, work through this list with your lawyer:
- Request a full three-year history of TMI and operating costs from the landlord.
- Confirm what is and is not included in "additional rent", in writing.
- Confirm who is responsible for HVAC maintenance and HVAC replacement.
- Confirm who is responsible for structural repairs (roof, foundation, walls).
- Check whether CAM charges are capped and whether capital improvements are excluded.
- Review the rent escalation clause, is the formula clear and capped?
- Review any personal guarantee, negotiate a burn-off, a dollar cap, and term limits.
- Understand leasehold improvement ownership and any restoration obligations at end of term.
- Review renewal options and the rent formula that will apply at renewal.
- Have a commercial lawyer review the full lease before you sign.
Frequently Asked Questions
What is TMI in a commercial lease?
TMI stands for Taxes, Maintenance, and Insurance. It is the additional rent a commercial tenant pays on top of base rent in a net lease, covering the tenant's proportionate share of property taxes, building and common-area maintenance, and building insurance. TMI does not cover your business contents, equipment, or liability insurance, you carry those separately.
Can a landlord increase commercial rent in Ontario?
Yes. Ontario's Commercial Tenancies Act does not cap commercial rent increases, and residential rent guidelines do not apply. Within the lease term, increases follow whatever escalation formula the lease specifies. At renewal, the landlord can propose any rent, so your protection depends entirely on the renewal options you negotiate before signing.
Who is responsible for HVAC in a commercial lease in Ontario?
There is no default rule in Ontario. Responsibility for HVAC maintenance and replacement depends entirely on what the lease says. In triple net leases, HVAC costs often fall to the tenant. Negotiate the split between repairs and capital replacement, and push for a dollar threshold above which responsibility shifts back to the landlord.
What is included in additional rent in a commercial lease?
Additional rent typically includes your proportionate share of property taxes, building insurance, and common area maintenance, often bundled as TMI or CAM. What qualifies depends on lease wording, which is why vague definitions are dangerous. Always request a written list of everything the landlord can include in additional rent.
What is the difference between a gross lease and a net lease?
In a gross lease, the tenant pays a fixed rent and the landlord covers taxes, insurance, and maintenance. In a net lease, the tenant pays base rent plus some or all of those costs. Triple net leases pass all three to the tenant. Gross rents look higher, but net rents can be unpredictable once additional costs are included.
What does the Commercial Tenancies Act say about operating costs?
The Commercial Tenancies Act does not regulate operating costs, TMI, or rent levels. It governs procedural matters like distress, lock-outs, and notice requirements, but the lease itself controls what a tenant pays. Ontario's government guidance confirms that a signed commercial lease takes precedence over the Act on these commercial terms.
How are CAM charges calculated in Ontario?
CAM charges are typically calculated by totaling the landlord's common-area costs for the year, dividing by the building's total rentable square footage, and multiplying by your leased square footage. The result is your proportionate share. The calculation itself is straightforward, the risk lies in what costs the landlord includes in the CAM pool in the first place.
What should I negotiate before signing a commercial lease in Ontario?
Focus on the items with the biggest financial exposure: caps on CAM and operating cost increases, exclusion of capital expenditures from TMI, HVAC and structural repair responsibility, a clear rent escalation formula, renewal rent terms, and any personal guarantee. Bring in a commercial lawyer before signing, not after.
This article is for general information only and does not constitute legal advice. Commercial leases are complex, and every situation is different. Consult a lawyer before signing or negotiating any commercial lease.
Sources & Official Resources
Ontario Statutes Cited
Government Guidance
- Renting Commercial Property in Ontario, Ontario Government
- Understanding Your Business Lease, FedDev Ontario
Contact Hadri Law
Before you sign a commercial lease, knowing what to look for can save your business thousands of dollars, and potentially your personal assets. Hadri Law advises businesses across Toronto, Mississauga, and the GTA on commercial lease review, negotiation, and strategy.
Call (437) 974-2374 for a free consultation, or book directly through our online scheduler at calendly.com/hadrilaw/free-consultation. Our team serves clients in English, French, Spanish, and Catalan.
