What Is Due Diligence When Buying a Business? The Buyer's Checklist

Q: How long does due diligence take when buying a business?

Plan on 30–60 days for a Main Street deal, running partly in parallel with SBA loan underwriting. Deals that eventually die drag longest — in Axial's study of broken LOIs, failed deals averaged 106 days under exclusivity before collapsing.

Q: What should a buyer check during due diligence?

Four buckets: financial (earnings quality, tax-return reconciliation, revenue by customer, inventory), legal (liens, contracts, leases, litigation, licenses), operational (equipment, suppliers, systems), and people (key employees, owner dependence, retention risk). Each bucket has a specialist — accountant, attorney, and you.

Q: What happens if due diligence finds problems?

Usually renegotiation, not collapse. Findings translate into a price adjustment, an escrow or holdback, or seller fixes before closing. Walking away entirely is the right answer when the core earnings were misrepresented — findings that cut claimed earnings also cut what a lender will finance, which re-prices the deal automatically.

By The Broker Index Team · October 2, 2026 · 9 min read

Illustration: The Broker Index

Due diligence is the 30–60 day inspection period between signing a letter of intent and closing, when you and your advisors verify that the business you agreed to buy is the business that actually exists. You've seen the broker's book; now you check it against tax returns, bank statements, contracts, and the parking lot at 7 a.m. It's tedious, it costs real money, and it's the cheapest insurance you'll ever buy: nearly half of all broken deals die because diligence found something — which means diligence worked.

Why deals die here — and why that's the system working

When Axial autopsied 75 broken LOIs, the two biggest killers were diligence findings (25.3%) and quality-of-earnings discrepancies (21.3%) — 46.6% combined. The dead deals averaged 106 days under exclusivity before collapsing. Read that from the buyer's chair: every one of those collapses was a purchase someone almost made at the wrong price.

Source: Axial, Dead Deal Report: Unpacking 2025's Broken LOIs (75 broken LOIs).

The checklist, bucket by bucket

Financial. Reconcile the P&L to the filed tax returns — the first and most telling test. Trace reported revenue to bank deposits. Get revenue by customer for three years and flag anyone over 15%. Test the add-backs behind the recast earnings (our SDE guide explains which survive scrutiny). On bigger deals, hire out a formal quality of earnings review — mandatory anyway for SBA deals of $3M+ since October 2026. Count the inventory yourself; don't accept the number on the sheet.

Legal. Your attorney runs UCC lien searches, reads the lease (is it assignable? how long is left? Landlords kill more small deals than lawyers do), reviews key contracts for change-of-control clauses, and checks litigation history and license transferability. Every lien must have a payoff plan before closing.

Operational. Walk the site more than once, unannounced if the confidentiality plan allows. Inspect the equipment list against reality and get repair estimates for anything tired. Talk to suppliers where possible. Ask what happens to the phone number, the website, the Google reviews — small assets that move revenue.

People. The bucket buyers skip, and the one that bites hardest. Who are the three employees the business can't run without, what do they know, and what keeps them after closing? How much of the revenue is loyal to the owner personally? You often can't interview staff before close (see why sellers keep sales quiet), so negotiate retention bonuses and a real transition period instead.

Worked example (hypothetical)

A buyer is under LOI at $800,000 for a parts distributor. Diligence finds two things. The CIM lists inventory at $120,000; a physical count finds $78,000 sellable (the rest is obsolete stock) — a $42,000 gap. The delivery fleet needs $25,000 of deferred maintenance the "well-maintained equipment" paragraph didn't mention.

Adjustment: $42,000 + $25,000 = $67,000, and the buyer recloses at $733,000 — an 8.4% price cut for roughly $20,000 of diligence spend. Neither finding killed the deal. Both findings paid for the inspection several times over. That's the normal outcome: renegotiation, not collapse.

46.6%of broken LOIs died on diligence or earnings findings

30–60 daystypical diligence window on a Main Street deal

106 daysaverage time under exclusivity before dead deals died

20–30%of listed businesses actually sell — verified ones close faster

Sources: Axial Dead Deal Report; Exit Planning Institute via DueDilio.

Two colleagues reviewing a stack of documents at an office desk — Thirty days of paperwork against years of regret. Fair trade. Photo: Unsplash

Running it well — for buyers and sellers both

Buyers: send one organized request list in week one, not a drip of surprises; work from a shared checklist with your accountant and attorney so nothing falls between chairs; and keep your LOI's exclusivity window tied to milestones so a stalling seller can't run out your clock. Budget properly — on deals under $1 million, outside diligence typically runs several percent of the purchase price — and spend it anyway.

Sellers: everything above is also your prep list, in reverse. The findings that cut prices are almost never surprises to the owner — the stale inventory, the month-to-month lease, the customer who's 40% of revenue. Fix or disclose them before the buyer's accountant finds them, and the renegotiation never happens. A good broker runs this pre-flight before listing; a listing mill discovers these problems at day 90, under exclusivity, at your expense. Worth knowing which kind you've hired beforehand.

Frequently asked questions

How long does due diligence take when buying a business?

Plan on 30–60 days, partly overlapping loan underwriting. Dead deals drag longest — broken LOIs averaged 106 days under exclusivity before collapsing.

What should a buyer check during due diligence?

Financial (earnings, tax reconciliation, customer concentration, inventory), legal (liens, lease, contracts, litigation), operational (equipment, suppliers), and people (key staff, owner dependence). Accountant, attorney, and your own eyes — all three.

What happens if due diligence finds problems?

Usually a renegotiation: price adjustment, escrow, or seller fixes. Walk away when the core earnings were misrepresented — findings that shrink earnings also shrink the loan, which re-prices the deal on its own.

Diligence the broker, too

The intermediary running your deal has a track record with past clients. Look them up — individual brokers, rated on six deal-specific parameters. Free, and brokers can't pay to polish it.

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