The ultimate seller's due diligence checklist: navigating the M&A process

The most expensive diligence miss I saw last year was a single missing contract. The buyer assumed the revenue was shaky and cut the price by 20%. We fixed it later, but the leverage was gone.

Here is the thing: a due diligence checklist for seller is not paperwork. It is how you keep control of price, timing, and terms when the buyer starts asking hard questions.

1. 01

   Reconcile financials

   Match management accounts to tax filings and explain variances before the buyer asks.
2. 02

   Document add-backs

   Attach invoices and payroll records to every adjustment so EBITDA is defensible.
3. 03

   Build a working capital bridge

   Show historical working capital levels so buyers cannot surprise you at close.

Contracts are where deals die. I have seen buyers walk when renewal terms were unclear or when customer concentration was hidden. A strong due diligence checklist for seller makes revenue visibility impossible to question.

• 01Provide customer contracts and renewal terms
• 02Show churn, retention, and pipeline conversion
• 03Disclose concentration risk and mitigation steps

Northfield Manufacturing had a clean financial package but missing customer contracts. The buyer paused diligence and used the gap to push for a lower multiple. Once we rebuilt the contract file and showed renewal history, the multiple recovered.

The lesson was simple: diligence is won by documentation, not promises. Understanding why quality of earnings matters helps you anticipate what buyers will challenge. Generate clean financial statements before the process starts.

• 01Rebuilt customer contract files
• 02Documented renewal history
• 03Restored buyer confidence in revenue

If you want a one-page view, here is the core of my due diligence checklist for seller. These are the items buyers ask for first. I keep this list on the first tab of the data room so nothing slips.

• 01Three years of financials and monthly management accounts
• 02Customer contracts, churn, and pipeline data
• 03Add-back schedule with evidence
• 04Org chart, key roles, and employment contracts
• 05Supplier and vendor agreements