Small Business Due Diligence Checklist for Buyers

Due diligence is where deals are won or lost. After your offer is accepted, this is your window to verify that the business is exactly what the seller claims — and to walk away cleanly if it isn't. The goal isn't paperwork for its own sake; it's protecting the cash flow you're about to pay for. Start with our downloadable buyer's due-diligence checklist and work through the areas below.

1. Reconcile the financials to tax returns

Never trust a seller's spreadsheet. Get three years of business tax returns, profit-and-loss statements, and bank statements, and confirm they tie out to each other. The reported revenue and SDE should reconcile to actual bank deposits and to what was filed with the IRS. A gap between the “real” numbers and the tax return is one of the most common ways deals fall apart — and it should.

2. Scrutinize the add-backs

SDE is built by adding back the owner's salary, personal expenses run through the business, one-time costs, interest, and depreciation. Some add-backs are legitimate; many are wishful. Challenge every line:

• Is this expense actually discretionary, or will you have to keep paying it?
• Is the “one-time” cost truly one-time, or recurring in disguise?
• Does the owner's add-back assume you'll work 60-hour weeks for free?

Inflated add-backs inflate SDE, and since price is SDE × multiple, every padded dollar can cost you several. Sanity-check the resulting valuation in the valuation calculator.

3. Test customer concentration

Get revenue broken down by customer. If a single customer is more than ~15–20% of revenue, losing them after closing could sink the business. Concentration isn't automatically a deal-killer, but it should change your price, your structure (more seller note or an earnout), or both.

4. Measure owner dependence

Ask the hard question: what happens to this business if the owner disappears? If the owner is the top salesperson, the only licensed person, or the relationship every customer trusts, the value can walk out the door at closing. Look for a real team, documented systems, and a path to keep key staff and licenses after the handoff.

5. Review the lease, contracts, and legal

• Lease: read it in full — remaining term, escalations, assignment rights, and personal guarantees. A short or non-transferable lease can make the business unsellable later.
• Contracts: confirm customer and vendor agreements transfer with the sale, and check renewal terms.
• Legal/compliance: licenses and permits, pending litigation, employee classification (1099 vs. W-2), and any back-tax exposure.

6. Know your walk-away triggers

Decide in advance what kills the deal, so emotion doesn't override the evidence. Common walk-away triggers:

• Numbers that won't reconcile to tax returns or bank deposits.
• Add-backs that collapse SDE once you remove the aggressive ones.
• A single customer or employee the business can't survive losing.
• A lease that won't transfer on workable terms.
• Undisclosed legal, tax, or environmental liabilities.
• A seller who won't provide documentation or stand behind their numbers.

Let the analyzer pressure-test the deal

Once your numbers are verified, run the deal through the AI Deal Analyzer to get a grounded valuation, a SOWS score, a multiple sanity-check, and a list of red flags and seller questions to chase down — so nothing slips through before you close.

Keep going

• Download the buyer's due-diligence checklist
• How to buy a small business (the full process)
• How to value a laundromat
• What's a fair multiple for an HVAC business?