Due diligence is the process by which a buyer verifies that the business they are acquiring is exactly what it appears to be — and uncovers anything that might change the deal terms, the price, or the decision to proceed at all. In off-market transactions, where the buyer has often developed a genuine relationship with the seller before reaching this stage, due diligence can feel like a breach of trust. It is not. It is a professional obligation that protects both parties: the buyer from purchasing something they do not fully understand, and the seller from future disputes over undisclosed issues that proper investigation would have surfaced. Every serious buyer must complete thorough due diligence before closing, regardless of how well they know the seller or how compelling the opportunity appears.

According to M&A advisory professionals and research published by the Association for Corporate Growth (ACG), inadequate due diligence is one of the most common contributors to post-closing disputes, purchase price adjustments, and failed integrations. The businesses that seem most straightforward on the surface are often the ones that reveal the most complexity under examination. A systematic, professionally managed due diligence process is not excessive caution — it is the standard of care that every competent acquirer applies to every transaction.

Financial Due Diligence

Financial due diligence is the foundation of the entire process. Its goal is to verify and normalize the historical financial performance of the business and to assess the quality and sustainability of future earnings. The primary output is a clear understanding of normalized EBITDA — the earnings that a new owner can actually expect to generate after removing owner-specific, non-recurring, and non-operating items.

• ✅ 3–5 years of tax returns and financial statements — compare reported income to tax filings to identify discrepancies
• ✅ Monthly revenue and expense detail — identify seasonality, trends, and anomalies
• ✅ Quality of Earnings analysis — verify that reported EBITDA reflects sustainable, recurring cash flows
• ✅ Accounts receivable aging — assess collectability and customer payment behavior
• ✅ Working capital analysis — establish the normalized working capital required to operate the business
• ✅ CapEx history and future requirements — understand the ongoing capital investment the business needs
• ✅ Debt obligations and off-balance-sheet liabilities — verify all obligations that will survive closing

Engaging a CPA firm experienced in M&A due diligence — rather than relying on the seller's accountant — is standard practice and strongly recommended. The cost of a professional QofE review ($15,000–$40,000 depending on deal size) is a small fraction of the risk it mitigates. According to transaction advisory research, buyers who conduct professional QofE reviews are significantly less likely to experience material post-closing financial surprises.

⚖️ Legal Due Diligence

Legal due diligence examines the legal health of the business — its contracts, obligations, IP, regulatory compliance, and litigation history. This is the domain of your M&A attorney, who will review the legal data room systematically and flag issues that need to be resolved before closing or addressed through representations and warranties in the purchase agreement.

• ✅ Corporate formation documents — confirm ownership structure and authority to sell
• ✅ Material contracts — customer agreements, supplier contracts, leases, and financing agreements
• ✅ Intellectual property ownership — patents, trademarks, copyrights, and trade secrets must be owned by the entity being sold, not the individual owner
• ✅ Employment agreements and non-competes — verify key employee arrangements and enforceability
• ✅ Litigation and regulatory history — any pending or threatened legal actions, regulatory violations, or environmental liabilities
• ✅ Insurance coverage — adequacy of existing policies and any claims history
• ✅ Permits and licenses — confirm that all required operating licenses are current and transferable

Operational Due Diligence

Operational due diligence examines how the business actually runs — its processes, people, technology, and competitive position. This is the dimension of due diligence that most distinguishes experienced acquirers from first-time buyers. Financial and legal due diligence can largely be delegated to professional advisors. Operational due diligence requires the buyer's own judgment and industry expertise.

Spend time in the business. Walk the facilities. Observe operations firsthand. Talk to management and key employees, with the seller's permission. Understand what happens on a typical day, who handles what, and what the business would look like if the owner stepped away tomorrow. Key person dependency — the risk that the business is operationally dependent on the selling owner in ways that will be difficult to replace — is one of the most significant and frequently underestimated risks in lower middle market acquisitions.

• ✅ Management team depth — who can run the business after the seller exits?
• ✅ Process documentation — are key operational processes documented, or does the knowledge live in the owner's head?
• ✅ Technology and systems — assess the adequacy of IT systems, software, and infrastructure
• ✅ Supply chain concentration — heavy dependence on one or two suppliers creates fragility
• ✅ Customer concentration — if 30%+ of revenue comes from a single customer, the business carries significant concentration risk
• ✅ Competitive landscape — assess barriers to entry and the business's competitive positioning

Customer and Revenue Quality Review

Understanding the quality and durability of the revenue base is one of the most critical and often underdone components of due diligence. A business with $2M in EBITDA concentrated in three customers is fundamentally different from one with the same EBITDA spread across 200 customers. Revenue quality analysis examines customer concentration, contract duration and renewal rates, average customer tenure, revenue mix between recurring and project-based work, and gross margin by customer and product line.

Request a complete customer list with associated revenue by year for the past three years. Look for customers who were significant in year one but have diminished or disappeared — this churn is a warning sign. Look for new customers who represent a large share of the most recent year revenue — heavy reliance on recently-acquired customers reduces the historical earnings credibility. And always, always check whether any major customers have relationships with the owner that may not survive the transition to new ownership.

?‍? HR and Employee Review

The people in a business are often its most valuable and most underexamined assets. HR due diligence covers the structure and terms of employment, compensation and benefits benchmarking, turnover rates, any pending employment claims, and the cultural dynamics that drive retention. In businesses where technical expertise or customer relationships are embedded in specific employees, understanding those employees' contractual obligations and retention likelihood is essential pre-closing work.

Ask for an organizational chart and a roster of all employees with compensation, tenure, and title. Identify the top five or ten people who are most critical to the business's continued performance. Understand what — if anything — binds them to the company (equity, non-competes, long-term agreements), and what risks exist if they depart post-closing. Developing a retention plan for key employees before closing — often including signing bonuses, equity participation, or explicit role-based guarantees — is a standard practice in well-managed acquisitions.

Once you have completed due diligence and are ready to close, our team can support you through the final stages. Contact our advisory team to discuss deal structure and transition planning, or explore our off-market deal sourcing process if you are still identifying your target business.

❓ Frequently Asked Questions

How long does due diligence typically take in a lower middle market acquisition?

Full due diligence typically takes 45–90 days in the lower middle market, depending on the complexity of the business. Simple, single-location service businesses with clean financials can sometimes be completed in 30–45 days. Multi-location businesses, those with complex regulatory environments, or those with significant real estate or IP components can take 90–120 days or longer.

Should I hire outside advisors for due diligence or do it myself?

Professional advisors are essential for financial and legal due diligence — these are specialized disciplines that require expertise most buyers do not possess. Operational and commercial due diligence often benefits from the buyer's own industry knowledge and judgment, supplemented where needed by industry consultants. The total cost of professional due diligence advisors for a lower middle market transaction typically ranges from $30,000 to $100,000 depending on deal size and complexity — a worthwhile investment relative to the risk being managed.

What happens when due diligence uncovers a problem?

Material due diligence findings do not automatically mean the deal is dead. Most findings result in one of three outcomes: a purchase price reduction to reflect the discovered risk, a change in deal structure (such as an escrow holdback or an expanded indemnification provision), or the seller agreeing to remediate the issue before closing. True walk-away findings — undisclosed fraud, irreparable environmental liability, existential customer concentration risk — are less common but must be taken seriously when they arise.

Final Thoughts

Due diligence is not an obstacle to closing a deal — it is the process by which both parties develop the shared understanding needed to close a deal that holds up over time. Buyers who approach due diligence as a collaborative investigation — working transparently with the seller to understand the business thoroughly — build the kind of trust that makes the post-closing transition smoother and more successful. Be thorough. Be professional. And never let relationship warmth substitute for factual verification.