TREADSTONE LAW · ONTARIO · DIGITAL LEGAL SERVICES · EST. MMXXI ·TSL
Home/Articles/Buying & Selling a Business
№ 124 Buying & Selling a Business

Due Diligence in a Partnership Buyout in Ontario: Why It Still Matters

Why Ontario partners buying out a co-owner still need real financial and legal due diligence, even when they think they already know the business.

Buying & Selling a Business5 min readTSLBy the Treadstone Law team · OntarioUpdated 2026-07
All articles
Key takeaways
  • Day-to-day familiarity with a business tends to cover operations — how customers are served, how the team functions, roughly how revenue is trending.
  • - Whether corporate and tax filings are actually up to date, not just "probably fine" - Whether any contracts contain change-of-control or consent provisions triggered by the buyout…
  • - [ ] Corporate records and minute book (is the corporation actually in good standing, and are past resolutions properly documented?) - [ ] Financial statements for recent years,…

If you've worked alongside your business partner for years, it's tempting to think due diligence is something outside buyers need — not you. You've seen the books. You know the customers. You were in the room for most of the decisions. Why pay for a formal review of a business you already understand?

Because knowing a business day-to-day and verifying its legal and financial position are two different things. Due diligence in a partnership buyout exists to confirm what you believe is true, uncover what you don't know, and create a documented record that protects you if something surfaces later — regardless of how well you know your co-owner.

This article explains what due diligence in a buyout actually covers and why skipping it is one of the more common regrets Ontario partners report after the fact.

"I Already Know This Business" Is a Trap

Day-to-day familiarity with a business tends to cover operations — how customers are served, how the team functions, roughly how revenue is trending. It rarely covers everything a proper legal and financial review would catch: undisclosed liabilities, contracts with terms you never read closely, tax filing gaps, or side arrangements your partner made without mentioning them. Partners are also not immune to disagreements about what "the business" actually includes, especially around personal expenses run through the company or informal understandings that were never written down.

What Familiarity Doesn't Tell You

What Real Due Diligence Covers in a Buyout

Financial Statements Deserve Special Scrutiny

Financial statements a partner has seen every year as an owner are not the same as financial statements reviewed specifically for a buyout, with an eye toward what the numbers mean for a price being paid today. Questions worth asking include: are there personal expenses running through the business that inflate or distort the numbers? Are there one-time items that make a normal year look unusually strong or weak? Has anything changed in how the business recognizes revenue or expenses that would make comparing years misleading? An accountant reviewing the statements specifically for the buyout — rather than for annual filing purposes — often catches things day-to-day familiarity misses entirely.

Where This Protects You Later

Due diligence isn't only about catching problems before you pay. It also creates a record of what was reviewed, what was disclosed, and what both sides understood at the time of the deal. If a disagreement surfaces after closing — about the state of the business, an undisclosed liability, or what was actually included in the price — that record is often what determines how the dispute gets resolved.

Frequently asked questions

How is due diligence between partners different from due diligence buying a stranger's business?

The categories reviewed are largely the same, but the emphasis often shifts. Partner buyouts tend to focus more heavily on personal-versus-business expenses, informal side arrangements, and confirming that both partners have the same understanding of what's included — issues that come up less often between strangers.

Can we skip due diligence if we're both being reasonable about the deal?

You can, but skipping it removes the documented record that protects both sides if a disagreement arises later. Being reasonable during negotiations doesn't prevent good-faith disagreements about facts from surfacing afterward.

Who pays for due diligence in a partner buyout?

This is a negotiated point, much like in any business sale, and there's no fixed rule. It's often split, built into the buyout costs, or allocated based on who is requesting which review — this is worth agreeing on explicitly rather than assuming.

Does the departing partner have to cooperate with due diligence?

Cooperation is typically expected and often addressed directly in the buyout agreement, since the departing partner usually has access to records and knowledge the remaining partner needs to review properly.

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.

This is a business purchase or sale question

Start a file online — flat, published fees, reviewed by a licensed Ontario lawyer before a dollar is owed.

ContactStart a File →