The due diligence phase is where deals are made – and where many fall apart. With a structured checklist and a clear process, you can investigate a business properly before committing serious time and money.
For many buyers, this stage is also the most stressful part of the acquisition journey. You may already be imagining what life will look like as the new owner. Perhaps you are thinking about the freedom of running your own company, or the financial upside if the business performs well.
But due diligence is the moment where optimism meets reality. Are the customers stable? Are there hidden risks buried in contracts or operations? If the answers hold up, you move forward with confidence. If they do not, you walk away – which can sometimes be the smartest decision a buyer makes.
In this guide we strip away the jargon and walk you through a simple twelve-step due diligence checklist designed for entrepreneurs, investors and first-time buyers evaluating a business acquisition in the United States.
Let’s dive in.
Due Diligence Checklist for Buying a Business (US)
Before we dive into each step, here is the condensed twelve-step checklist at a glance. Many buyers find it helpful to copy this into a working document and tick off each item as they move through the investigation process.
At first glance the list can look intimidating. That is normal. Buying a business involves many moving parts, and the due diligence phase is where you examine them carefully.
The good news is that not every item will apply to every transaction. A service business will have different risks than a manufacturing company, and a small owner-operated firm will require less investigation than a multi-location operation.
Think of this checklist as a framework rather than a rigid formula. It helps ensure that you do not overlook the areas where buyers most commonly get surprised.
- Set-Up: timeline, document request list, advisory team, confidentiality agreements
- Financial Due Diligence: financial statements, tax returns, revenue verification, AR/AP review, working capital
- Inventory: stock reports, saleable inventory, independent counts
- Assets & Equipment: asset register, ownership vs leases, maintenance history
- Sales: revenue sources, pricing structure, customer concentration, CRM systems
- Marketing: marketing strategy, channels, brand positioning, digital presence
- People / HR: employee roles, compensation, payroll compliance, benefits, contractor classification
- Systems & Operations: accounting software, processes, IT access, internal controls
- Customers, Suppliers & Competition: market analysis, supplier dependence, customer relationships
- Contracts & Legal: leases, contracts, licenses, liens, litigation and compliance
- Pro Forma: acquisition financial model and break-even forecast
- Decision & Renegotiation: price adjustments, risk mitigation, closing strategy
Once you begin working through these steps, the process becomes far less overwhelming. Each item simply represents another piece of the puzzle.
Step 1: Get the Process Set Up
Before reviewing documents in detail, establish a clear structure for the due diligence phase.
Agree on a realistic timeline with the seller. For many small business acquisitions around 20 business days is typical, although more complex transactions can take longer.
Create a document request list outlining exactly what information you will need. This typically includes financial statements, contracts, payroll records, customer reports and tax filings.
You should also assemble a small advisory team. Most buyers rely on an accountant to review the financial information and a business attorney to examine contracts and legal risks. Some buyers also recruit a partner or trusted colleague to help with operational tasks such as inventory checks or data gathering.
Tip: Our article Do You Need an Right Accountant or Lawyer When Buying a Business ? can provide some more advice on this front.
Confidentiality is another key issue. Sellers may want to limit who knows about the potential sale, particularly employees or customers. Make sure you understand what access you will have and who you are permitted to speak with. If a seller restricts access too heavily, it can be a warning sign.
Step 2: Financial Due Diligence
Your objective here is simple: confirm that the financial performance used to value the business is accurate.
At minimum you should request three years of financial statements and business tax returns. These typically include profit-and-loss statements, balance sheets and internal monthly reports. In the United States you should review both federal and state tax filings, along with payroll tax and sales tax records where applicable.
A common verification technique is sampling and tracing. Sampling means selecting a spread of invoices across different months and years, rather than auditing every transaction. Tracing means following the trail from invoice → payment → bank deposit to confirm the revenue is genuine.
What you are looking for above all is consistency. Sudden margin swings, unusual one-off transactions or unexplained cost changes should always be investigated.
Your financial due diligence checklist should include:
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Owner add-backs – confirm that personal expenses added back to profit are legitimate.
• Accounts receivable (AR) – unpaid invoices and average collection times.
• Accounts payable (AP) – supplier balances and payment patterns.
• Debt and credit facilities – loan terms, interest rates and any lender covenants.
In the US it is sometimes possible to verify tax filings with the IRS if the seller signs a transcript request form. While not always necessary, it can provide an additional layer of confirmation.
You should also confirm that the business has properly collected and remitted sales tax, which varies by state and can create significant liabilities if mishandled.
Tip: Our article Financial Due Diligence: What Every Business Buyer Needs to Know delves into this part of the process in more detail.
Step 3: Inventory Due Diligence
If the business sells physical products, inventory becomes an important part of the valuation.
This is also one of the areas where buyers occasionally get unpleasant surprises. A balance sheet might show hundreds of thousands of dollars in inventory, but once you dig deeper you may discover that a large portion of it has been sitting on the shelves for years.
Request a detailed inventory report and identify which items qualify as good and saleable stock. Slow-moving, obsolete or damaged items may have little real value, even if they appear valuable on paper.
Whenever possible, perform an independent inventory count rather than relying solely on the seller’s figures. This can feel a little awkward at first, especially if the owner wants to help, but it is important that you see the inventory with your own eyes.
The counted inventory should broadly align with the balance sheet. If significant discrepancies appear, the purchase price may need to be adjusted.
Step 4: Assets & Equipment
Many businesses rely heavily on physical equipment, vehicles or machinery. Understanding the condition and ownership of these assets is essential.
Create an asset register listing the major items used in operations. Confirm whether each asset is owned outright or financed through a lease or equipment loan.
Review maintenance history, warranties and the expected remaining lifespan of critical equipment. Estimating replacement costs is equally important, since major failures shortly after acquisition can quickly drain working capital.
Step 5: Sales Due Diligence
Understanding how the company actually generates revenue is critical. How does the business attract leads? Are customers primarily repeat buyers, referrals or one-time purchasers? How visible is the sales pipeline?
You should also examine pricing policies, discounting practices and the company’s use of CRM software to track prospects and customers.
Customer concentration deserves particular attention. If a large share of revenue depends on a few clients or salespeople, the business may be vulnerable after ownership changes.
At the same time, this step often reveals growth opportunities such as new markets, additional product lines or improvements to the sales process.
Step 6: Marketing Due Diligence
Marketing due diligence looks at how the business attracts and retains customers.
Evaluate the company’s marketing channels, brand positioning and digital presence. Many small businesses have outdated websites, weak social media activity or minimal data tracking.
A positive sign is a structured marketing plan that clearly outlines budgets, campaigns and expected results. In many acquisitions, improving marketing is one of the fastest ways to increase revenue after the transition.
Tip: For a case study in how updating an old business’ digital presence and marketing strategy can lead to success, read These Families Changed Their Lives by Buying a Business - And You Can Too
Step 7: People and HR
Employees can be one of the most valuable – and sensitive – parts of a business acquisition.
In the United States employment is often at-will, but that does not remove risk. During due diligence you should review employee roles, compensation structures, payroll practices and benefit plans such as health insurance or retirement programs.
It is also important to confirm that workers are classified correctly as employees or independent contractors, often referred to as W-2 versus 1099 classification. Misclassification can create regulatory penalties and tax liabilities.
Finally, identify key employees whose departure could disrupt operations shortly after the acquisition.
Step 8: Systems and Operations
A well-run business should not rely entirely on the owner’s personal knowledge.
Evaluate the company’s internal systems and operational processes. Businesses with documented procedures and clear reporting structures are far easier to transition to new ownership.
Review the accounting software, operational workflows and internal reporting practices. You should also confirm who has access to critical systems, banking controls and digital accounts, including domains and administrative passwords.
Tip: For a closer look at why the best way to sell a business is to make it run independently from you, read The Smartest Way to Sell Your Business? Make Yourself Redundant
Step 9: Customers, Suppliers and Competition
External relationships matter just as much as internal operations. Research competitors operating within the same industry and geographic market. Compare pricing, positioning and customer feedback to understand where the target business fits.
Supplier relationships also deserve attention. Heavy dependence on a single vendor can create operational risk.
Finally, analyze the customer base carefully. Understanding who buys from the business – and why – will help you evaluate both risk and long-term growth potential.
Step 10: Contracts and Legal Due Diligence
Legal due diligence is one area where professional guidance is highly recommended. An experienced business attorney can identify contractual risks that may not be obvious to buyers.
Your legal due diligence checklist should include:
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Leases – assignment clauses, renewal options and total occupancy costs.
• Insurance – required coverage and the cost of replacement policies.
• Contracts – supplier, customer and employment agreements and any transfer restrictions.
• Licenses and permits – regulatory approvals required for the industry.
• Corporate records – incorporation documents and good-standing certificates from the state.
• Litigation and compliance – lawsuits, environmental issues or regulatory investigations.
In the United States it is also important to perform a UCC lien search to determine whether lenders hold security interests over the company’s assets. Buyers should also review change-of-control clauses in loan agreements and major contracts, since these provisions can require lender approval before ownership transfers.
Finally, confirm that the business complies with zoning regulations, health department requirements and environmental rules where applicable.
Step 11: Build a Conservative Pro Forma
A pro forma is a forward-looking financial projection showing how the business may perform after the acquisition.
Start with a conservative revenue estimate and subtract Cost of Goods Sold (COGS) to determine gross profit. From that figure subtract operating expenses, debt payments from acquisition financing, professional fees, capital expenditure allowances and your own salary. The result is a projected net profit.
A realistic pro forma should also account for seasonality and help you determine the company’s break-even point. Most importantly, it should stress-test downside scenarios rather than relying on optimistic projections.
Step 12: Decision and Renegotiation
Congratulations – you made it all the way to the final step! Once due diligence is complete, the negotiation phase begins.
The information uncovered during your investigation becomes the basis for adjusting the purchase price or restructuring the deal. Buyers often use mechanisms such as escrow agreements, seller financing or earn-outs to manage risk.
Tip: Remember that good negotiation is about communicating clearly, not ‘winning’. For a deeper dive into the strategies and psychology of the negotiation phase, read our article How to Negotiate when Buying a Business.
Even after investing time and effort in due diligence, the most important skill for a buyer is the ability to walk away from a bad deal. Buying the wrong business can cost far more time and money than abandoning an acquisition after careful investigation. And if you do walk away, remember that there will always be other opportunities waiting.
And if you do have to walk away, no worries – there’s over 58,000 more businesses for sale on BusinessesForSale.com!