The main diligence categories
Due diligence is the process by which a buyer independently verifies everything represented during marketing. It typically spans several parallel tracks, each run by a different specialist on the buyer's team.
- 01
Financial diligence
Verifying reported earnings, often through a formal quality of earnings report. See our Quality of Earnings guide.
- 02
Legal diligence
Contracts, litigation history, IP ownership, regulatory compliance, and corporate structure.
- 03
Commercial diligence
Customer concentration, contract terms, competitive position, and growth sustainability.
- 04
Operational diligence
Key-person dependence, systems, processes, and how the business would run post-close.
- 05
Tax diligence
Historical tax filings, structuring implications, and any contingent tax liabilities.
A cautionary real case
In 2011, HP acquired British software company Autonomy for roughly $11 billion. Just over a year later, HP wrote down $8.8 billion of that value, alleging that Autonomy's prior management had misrepresented its financial performance, including revenue recognition practices that diligence should have caught before closing. Read CNN's original coverage ↗
The case became a widely cited example in corporate governance and M&A literature of what happens when diligence is treated as a formality rather than genuine verification, and it involved a Fortune 500 acquirer with a full internal M&A team, not a first-time buyer. Scale doesn't substitute for thoroughness.
Preparing for diligence as a seller
- →Assemble your data room before you go to market, not after an LOI is signed.
- →Have documentation ready for every add-back and unusual line item in your financials.
- →Know your customer concentration numbers cold. This is one of the first things a buyer's commercial diligence team asks about.
- →Consider a sell-side quality of earnings report to control the narrative on your own numbers before a buyer's team does.
How long diligence typically takes
For a lower-middle-market transaction, diligence commonly runs 60 to 90 days from LOI signing to closing, though complex deals or those involving regulatory approval can take considerably longer. See our How to Sell a Business guide for how this fits into the full process timeline.