Due diligence is the phase of an M&A transaction where everything either holds together or falls apart. Deals that seemed certain at the LOI stage collapse during due diligence every day — not because the business isn't valuable, but because the financial documentation doesn't support the story that was told to get the deal started.
Understanding what's coming — and preparing for it — is the difference between a clean close and a painful renegotiation.
What Due Diligence Actually Is
Financial due diligence is the buyer's systematic verification of everything the seller has represented about the business. Revenue quality. Expense sustainability. Working capital requirements. Customer concentration. Off-balance-sheet liabilities. Historical trends vs. forward projections. Every claim gets tested against documentation.
For sellers, due diligence is not just about surviving scrutiny. It's about presenting your business in a way that tells a compelling, defensible story — one that supports the valuation you negotiated and gives the buyer confidence to close.
The Documents You'll Need — Seller's Checklist
- 3 years of financial statements (P&L, balance sheet, cash flow) — reviewed or audited preferred
- 3 years of business and personal tax returns
- 12–24 months of bank statements for all accounts
- Accounts receivable aging report — current and 12 months back
- Accounts payable aging report
- Customer revenue breakdown — top 10–20 customers by revenue contribution
- Revenue by month for 36 months — showing seasonality and trend
- Employee roster with compensation, tenure, and role
- All material contracts — leases, vendor agreements, customer contracts
- Equipment list with condition and estimated useful life
- Any pending litigation, IRS notices, or regulatory issues
The Quality of Earnings Review
On any deal above $2M–$3M, the buyer will commission a Quality of Earnings report. This goes beyond verifying the numbers — it assesses whether the earnings are real, recurring, and sustainable post-acquisition.
The QoE team will recast your EBITDA — adding back non-recurring expenses, normalizing owner compensation, removing personal expenses, and adjusting for any one-time revenue items. The normalized EBITDA they arrive at is the number the valuation is based on. If it's lower than what you represented, expect a conversation about purchase price adjustment.
Working Capital Analysis
Every business requires a certain level of working capital to operate — receivables minus payables minus accrued liabilities. In most acquisitions, the purchase price assumes the business will be delivered with a normalized working capital balance. If it comes in below target, the difference comes out of your proceeds. Understanding and negotiating the working capital peg before close is one of the most financially consequential parts of the deal.
What Kills Deals During Due Diligence
The most common deal killers are not dramatic revelations. They're accumulated inconsistencies — revenue that doesn't match bank deposits, expenses that don't match tax returns, customer concentration that wasn't disclosed, or verbal representations that aren't supported by documentation. Each inconsistency alone might be explainable. Together, they erode buyer confidence in ways that are very difficult to recover from.
The Seller's Role During Due Diligence
Respond completely and promptly to every information request. Provide context proactively for anything that looks unusual. Don't hide problems — surface them yourself, with explanation. Buyers expect imperfect businesses. They don't tolerate discovering problems they weren't told about.
At TaxBooksCFO, we prepare our clients for due diligence long before a buyer arrives — so that when the process starts, the documentation is organized, the story is consistent, and the numbers are defensible.