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Reviewing Material Contracts Before Buying a Business in Ontario

Learn which contracts count as material in an Ontario business purchase, and why a buyer needs to read them before relying on the seller's revenue.

Buying & Selling a Business6 min readTSLBy the Treadstone Law team · OntarioUpdated 2026-07
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Key takeaways
  • There's no single legal test — it comes down to how much the contract matters to the value of what you're buying.
  • Reading a contract's headline terms isn't enough — certain clauses can materially change what you're actually buying: - Assignment and change-of-control clauses.

A business's revenue is only as reliable as the contracts behind it. A seller's summary of "long-term customer relationships" or "a solid supplier arrangement" means very little until you've actually read the underlying agreements — because a contract can be cancelled on short notice, assigned away by the seller, or quietly terminated the moment the business changes hands, no matter how it's been described to you.

Reviewing material contracts is one of the more time-consuming parts of due diligence, and one of the easiest to underinvest in when a deal is moving quickly. This article explains what makes a contract material, what to look for, and why it matters to the price you're paying.

What Makes a Contract "Material"?

There's no single legal test — it comes down to how much the contract matters to the value of what you're buying. A contract is generally worth close review if it involves any of the following:

A contract that's small in dollar terms but hard to replace — a sole-source supplier, for instance — can be just as material as a large customer agreement.

Categories of Contracts Worth a Close Read

CategoryWhy It Matters
Major customer agreementsConcentrated revenue is only as reliable as the contract securing it
Supplier and vendor agreementsLoss of a key supplier can disrupt operations immediately
Commercial leasesAssigning a lease generally needs landlord consent, and lease terms shape what the business can actually do at that location
Licensing and IP agreementsConfirms the business actually has the right to use what it's selling or operating under
Financing and loan agreementsReveals security interests, guarantees, and repayment obligations that may need to be dealt with at closing
Key employment or consulting agreementsIdentifies retention risk and any obligations tied to people the business depends on
Franchise agreements (if applicable)Franchise transfers involve separate disclosure and consent requirements under the Arthur Wishart Act (Franchise Disclosure), 2000

Clauses That Can Upend a Deal

Reading a contract's headline terms isn't enough — certain clauses can materially change what you're actually buying:

Why This Matters for the Revenue You're Relying On

Your offer for the business is built on an assumption that its current contracts will keep generating revenue after closing. If a major customer contract can be terminated on short notice, or a key supplier agreement doesn't survive a change of ownership, the business you actually end up owning may look meaningfully different from the one described in the financial statements. This is exactly why contract review sits alongside financial due diligence rather than after it — the numbers and the contracts need to be read together.

Getting the Contracts Into the Deal Properly

Frequently asked questions

Does every contract need to be reviewed, or just the big ones?

Focus your time on contracts that are material to the business's value — large revenue contributors, hard-to-replace suppliers, and anything tied to real property, key equipment, or personal guarantees. Smaller, routine, easily replaceable contracts generally warrant less scrutiny.

What happens if a contract needs consent to assign and the other party refuses?

It depends on the contract and the deal structure. Sometimes the parties negotiate around it, sometimes the contract is excluded from the deal, and sometimes it becomes a condition that must be resolved before closing. This is exactly why consent requirements should be identified early, not discovered at the closing table.

Does a share purchase avoid the need to review contracts as closely?

Not really — the contracts still matter just as much to the value of the business, but the mechanics differ. In a share purchase, contracts generally stay with the corporation without needing assignment, unless the contract itself includes a change-of-control clause triggered by the sale. In an asset purchase, contracts typically need to be formally assigned, which is more likely to require third-party consent.

Who should review the contracts — the buyer, or a lawyer?

Both. You know the business operationally and can flag what seems important; a lawyer is best placed to spot the assignment, termination, and change-of-control language that isn't always obvious from a plain read of the contract.

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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