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№ 22 Buying & Selling a Business

Assuming a Lease vs. Taking on New Liability When Buying a Business in Ontario

Assuming a business's lease means more than moving in. Learn which obligations transfer to an Ontario buyer, and which stay behind with the seller.

Buying & Selling a Business5 min readTSLBy the Treadstone Law team · OntarioUpdated 2026-07
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Key takeaways
  • In an asset purchase, nothing transfers automatically just because it's connected to the business — the buyer and seller specifically agree, contract by contract, what's being taken on.
  • Once an assignment is complete, the buyer generally takes on, from the assignment date forward: - Ongoing rent and additional rent — common area costs, property tax allocations, and…
  • - Rent or other charges that came due before the assignment date, unless the buyer specifically agrees to assume them - Disputes with the landlord that arose before the assignment, over…

When a business purchase includes leased premises, buyers often talk about "assuming the lease" as though it's a simple, contained step — sign an assignment, get the landlord's consent, and move in. In reality, assuming a lease means stepping into an ongoing set of legal obligations, some of which are obvious and some of which aren't.

Understanding exactly what comes with the lease, and what stays behind with the seller, is part of the broader asset-versus-share analysis that shapes every Ontario business purchase, but leases have their own specific wrinkles worth walking through on their own.

What "Assuming the Lease" Actually Means

In an asset purchase, nothing transfers automatically just because it's connected to the business — the buyer and seller specifically agree, contract by contract, what's being taken on. A lease is typically handled through a formal assignment, where the buyer becomes the tenant under the existing lease, subject to the landlord's consent.

In a share purchase, this issue mostly disappears: the corporation that holds the lease doesn't change, so there's usually nothing to assign at all — though a lease's change-of-control clause, if it has one, can still require landlord consent even in a share deal.

Obligations the Buyer Takes On

Once an assignment is complete, the buyer generally takes on, from the assignment date forward:

Liabilities That Generally Stay With the Seller

Quick Comparison

QuestionBuyer's Position After AssignmentSeller's Position After Assignment
Future rent and lease obligationsBuyer's responsibilityGenerally released, but see below
Pre-assignment arrearsNot assumed unless agreedSeller's debt, unless landlord agrees otherwise
Landlord's remedies, such as distress or re-entryApply to buyer as new tenantNo longer directly relevant once assigned
Ongoing liability to the landlordNew, direct liability under the leaseCan remain secondarily liable unless released
Pre-existing disputes with the landlordGenerally not inheritedStays with seller

Where the Line Gets Blurry

A few areas deserve extra attention, because "the buyer takes the lease going forward, the seller keeps the past" doesn't always play out that cleanly:

Frequently asked questions

If I assume the lease, am I responsible for the previous tenant's unpaid rent?

Generally not, unless you specifically agree to take it on. But because a landlord's remedies attach to the premises, it's important to confirm the lease is in good standing, ideally through a written landlord estoppel, before closing, rather than relying on the assumption alone.

Does assigning the lease release the seller completely?

Not automatically. Under general landlord-tenant principles, the outgoing tenant can remain secondarily liable to the landlord unless specifically released. Sellers should try to negotiate a release as part of the consent process.

Do I need landlord consent even in a share purchase?

Not always — because the corporate tenant doesn't change in a share deal, many leases don't require consent at all. But some leases specifically define a change of control as requiring consent, so the lease needs to be checked either way.

What's the difference between assuming a lease and assuming a liability generally?

Assuming a lease is one specific example of assuming a liability — an ongoing, defined set of obligations tied to a particular contract. In an asset purchase, every other liability, such as trade debts, litigation, or tax exposure, is negotiated separately and doesn't transfer just because the lease does.

This article is general information, not legal advice. Reading it does not create a lawyer-client relationship. Ontario laws, tax rates, and government programs change, and how the law applies depends on your specific facts. For advice about your situation, speak with a licensed Ontario lawyer. Treadstone Law is licensed by the Law Society of Ontario — reach us at 1-844-900-1070 or start a file online.

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