Financial due diligence, explained

Financial due diligence is the work of checking whether a company's numbers are real, repeatable, and worth the price — before money changes hands. It's a handful of distinct techniques, each answering a different question about the same set of financials. This guide maps them and links to a plain-English explainer for each.

Whether you're buying a business, lending against it, or auditing it, the same core concepts keep showing up. Here's how they fit together.

Earnings: is the profit real?

Before anyone argues about price, they argue about the earnings the price is built on. Two tools do most of that work.

A quality of earnings analysis is the independent test of whether reported earnings are real, repeatable, and sustainable — stripping out one-time, owner-specific, and non-operating items to find what the business actually earns on a go-forward basis. At its center sits the EBITDA bridge: the waterfall that walks reported EBITDA to an adjusted figure, with every add-back justified, because buyers pay a multiple of that number.

Deal mechanics: what gets handed over

Price is only half the deal. The other half is what's left in the business at closing — its working capital. Net working capital normalization sets the "peg," the normal operating liquidity the seller must deliver, and the deal trues up against it dollar-for-dollar. Get the definition wrong and the disputes start months after close.

Valuation and risk

Once the earnings base is clean, two lenses turn it into a view on value and survival. WACC — the weighted average cost of capital — is the discount rate that converts future cash flows into a present value (and the hurdle every project has to clear). The Altman Z-Score goes the other way: five ratios rolled into one number that flags how close a company is to distress.

The controls behind the numbers

None of the above means anything if the underlying transactions aren't real. Two controls test exactly that. The three-way match checks that what was ordered, received, and billed all agree — and the same logic, applied to sales orders and shipping documents, is how auditors test that revenue is recognized in the right period. SOX control testing is how a public company proves those controls are designed well and operating effectively under Section 404.

How they connect

Read together, these aren't seven separate topics — they're one workflow. Controls make the transactions trustworthy; the quality-of-earnings work normalizes them into a defensible EBITDA via the bridge; working capital sets what's delivered; and WACC and the Z-Score translate the result into value and risk. The concept in every case is simple. The work — and the defensibility — is in tying each figure back to its source.

Bottom line

Financial due diligence is less a single procedure than a toolkit: earnings quality, the EBITDA bridge, working capital, valuation, distress risk, and the controls underneath them. Start with whichever question you're facing — each explainer above is self-contained — and the rest connect from there.

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This guide is for general information and is not accounting, audit, tax, or investment advice. The methods it links to depend on your specific facts and should be prepared or reviewed by a qualified professional.