The Complete Due Diligence Checklist: What Buyers Will Ask For When You Sell Your Business

Due diligence is the process where buyers verify every claim you’ve made about your business — financials, operations, legal standing, customer relationships, and risk profile. It’s the most stressful phase of any M&A transaction because it’s where deals get repriced, restructured, or killed entirely. For business owners in the lower middle market ($3 million to $50 million in revenue), being prepared for due diligence before it starts is the single most important thing you can do to protect your purchase price and keep your deal on track.

Here’s what buyers actually ask for, organized by category, so you know exactly what to prepare.

Financial Due Diligence

Financial diligence is the most intensive area and where most surprises occur. Buyers (and their accounting firms) will request:

Historical financial statements — three to five years of income statements, balance sheets, and cash flow statements. Audited or reviewed statements are strongly preferred. Compiled or internally prepared statements will receive more scrutiny and may trigger additional verification procedures.

Tax returns — three to five years of federal and state returns for the business entity and any related entities. Buyers cross-reference tax returns against financial statements to identify discrepancies.

Quality of earnings analysis — buyers will typically hire a third-party accounting firm to conduct a QoE, which verifies adjusted EBITDA, normalizes one-time items, and assesses the sustainability of earnings. Having your own sell-side QoE prepared before going to market is a significant advantage.

Monthly financial detail — monthly P&L statements, revenue by customer, revenue by product/service line, and monthly cash flow for the trailing 24 months. This level of granularity helps buyers understand seasonality, trends, and concentration.

Accounts receivable and payable aging — current AR and AP aging schedules, historical write-offs, and collection patterns. Significant aged receivables or a history of write-offs signal revenue quality issues.

Capital expenditure history and projections — what you’ve spent on equipment, facilities, and technology, and what the business will need going forward. Deferred capex becomes a negotiation point because the buyer will need to make those investments post-close.

Legal Due Diligence

Legal diligence examines the contractual and regulatory framework of your business.

Corporate documents — articles of incorporation or organization, operating agreements, bylaws, shareholder agreements, and any amendments. These establish ownership, governance, and any transfer restrictions that could affect the transaction.

Material contracts — customer agreements, vendor contracts, lease agreements, partnership agreements, and any other contracts that are material to the business (typically defined as contracts above a certain dollar threshold or involving key relationships). Buyers want to see contract terms, renewal provisions, assignment clauses, and change-of-control provisions.

Employment agreements — offer letters, employment contracts, non-compete agreements, non-disclosure agreements, and IP assignment provisions for all key employees. Missing non-competes or IP assignments for key personnel are common and correctable issues — but they need to be addressed before or during the transaction.

Litigation and disputes — any pending, threatened, or historical litigation, arbitration, regulatory actions, or material disputes. Full disclosure is critical — undisclosed litigation discovered during diligence is a trust-destroying event that can kill deals.

Intellectual property — trademarks, patents, copyrights, trade secrets, domain names, and any licenses (inbound or outbound). Buyers want to confirm that the business owns or has proper licenses for all IP used in operations.

Regulatory compliance — permits, licenses, certifications, and compliance documentation relevant to your industry. Healthcare, financial services, environmental, food safety, and construction businesses face particularly rigorous regulatory diligence.

Operational Due Diligence

Operational diligence assesses whether the business can function and grow post-acquisition.

Organizational chart and employee roster — complete employee list including titles, compensation, tenure, benefits, and reporting relationships. Buyers evaluate management depth, key person dependencies, and total compensation burden.

Customer analysis — top 10-20 customers by revenue, customer retention rates, revenue concentration percentages, contract status, and relationship history. Buyers may request direct customer calls (typically with your top 3-5 accounts) to verify relationship strength and retention likelihood.

Vendor and supplier relationships — key vendor list, contract terms, alternative sourcing options, and any vendor concentration risks. Supply chain resilience has become an increasingly important diligence focus since 2020.

Technology and systems — IT infrastructure, software systems, cybersecurity practices, data management, and technology roadmap. For technology-dependent businesses, this can be one of the most extensive diligence areas.

Facilities and equipment — property condition assessments, equipment lists with age and condition ratings, lease terms for any leased equipment, and maintenance records. If real estate is involved, additional real estate-specific diligence applies.

Insurance and Risk Due Diligence

Insurance diligence has become increasingly sophisticated, particularly when PE firms are the buyers.

Insurance policies — complete copies of all active insurance policies: general liability, professional liability (E&O), D&O, cyber liability, EPLI, workers’ compensation, property, auto, umbrella, and any industry-specific coverage.

Claims history — five years of loss runs (claims history reports) from all carriers. Buyers evaluate both the frequency and severity of claims to assess risk profile and future insurability.

Coverage adequacy assessment — buyers compare your current coverage to their internal benchmarks and to industry standards. Gaps between your coverage and buyer expectations become negotiation points — either as price adjustments, escrow holdbacks, or closing conditions requiring additional coverage.

Working with an experienced commercial insurance advisor to review and optimize your coverage before entering diligence prevents surprises and demonstrates the kind of risk management maturity that sophisticated buyers value.

Banking and Financial Infrastructure Due Diligence

Banking relationships — list of all banking relationships, account types, balances, credit facilities, and loan agreements. Buyers need to understand existing debt that must be paid off at closing, available credit that supports operations, and the overall financial infrastructure.

Debt schedule — complete list of all outstanding debt including term loans, lines of credit, equipment financing, SBA loans, and any personal guarantees. Debt payoff amounts at closing directly affect net proceeds to the seller.

Financial controls and processes — internal controls, approval authorities, reconciliation procedures, and financial reporting cadence. Buyers assess whether the financial infrastructure can support post-acquisition reporting requirements — particularly relevant for PE buyers who require monthly financial packages.

How to Prepare: The Pre-Diligence Checklist

The best time to prepare for due diligence is 6-12 months before you plan to go to market. Here’s the high-level preparation framework:

Organize a virtual data room with all documents categorized and indexed. Platforms like Datasite, Intralinks, or even a well-organized SharePoint or Google Drive structure work for lower middle market deals.

Get your financials diligence-ready. If you don’t have audited or reviewed financials, consider engaging a CPA firm now. At minimum, ensure your internally prepared statements are clean, consistent, and reconcilable to tax returns.

Review all material contracts — identify any that are expired, unsigned, or missing key provisions (like assignment clauses). Fix what you can. Disclose what you can’t.

Conduct an internal legal audit — employment agreements, IP assignments, regulatory compliance, and corporate governance documents should all be current and complete.

Review your insurance program through a buyer’s lens. Gaps discovered now are fixable. Gaps discovered during buyer diligence become costly negotiation items.

Document your operations — processes, procedures, and institutional knowledge that currently lives in people’s heads needs to be captured in writing. This reduces perceived owner dependency and makes the business more transferable.

At Icon Business Advisors, due diligence preparation is a core component of our sell-side advisory process. We work with owners to build a comprehensive data room, identify and address potential diligence issues proactively, and coordinate with insurance, banking, legal, and accounting advisors to ensure the business presents at its best when buyers start asking questions.

Daniel Askew is the Founder and CEO of Icon Business Advisors, a Nashville-based M&A advisory firm serving lower middle market business owners ($3M–$50M revenue) with sell-side transactions, capital raising, business valuations, and strategic consulting.

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