What Is Depreciation? Why Investors Need to Understand It

Depreciation is an accounting concept that confuses many investors — and for good reason. It's an expense that reduces reported earnings, but no cash actually leaves the company when it's recorded. Understanding depreciation is essential because it directly affects two critical investor tools: owner earnings (which adds it back) and free cash flow (which adjusts for it indirectly).

How Depreciation Works

When a company buys a long-lived asset — a factory, a delivery truck, a piece of equipment — it doesn't expense the entire cost in the year of purchase. Instead, accounting rules require the cost to be spread over the asset's expected useful life. A $10 million machine with a 10-year useful life is "depreciated" at $1 million per year for a decade.

Each year, that $1 million shows up as a depreciation expense on the income statement, reducing reported earnings. But no cash was spent that year — the $10 million was spent when the machine was purchased, which showed up on the cash flow statement as a capital expenditure. Depreciation is the accounting echo of a past cash outflow, not a current one.

Amortization works identically but applies to intangible assets — patents, customer lists, software, and goodwill acquired through acquisitions. When investors say "D&A" (depreciation and amortization), they're referring to both concepts together.

Why Depreciation Matters for Investors

It Distorts Reported Earnings

Because depreciation reduces net income without reducing cash, reported earnings understate actual cash generation for capital-intensive businesses. A company reporting $2 billion in net income with $3 billion in depreciation actually generated $5 billion in pre-CapEx cash. Judging this company solely by its net income would dramatically underestimate its economic output.

This is exactly why owner earnings and free cash flow add depreciation back — they're correcting for the non-cash nature of the expense to reveal the actual cash the business produces.

It Connects to Capital Expenditures

Depreciation and CapEx are two sides of the same coin. Depreciation accounts for past capital spending; CapEx is current capital spending. For a stable business, annual depreciation and annual CapEx tend to be roughly similar — the company is spending about as much replacing assets as it's depreciating existing ones.

When CapEx significantly exceeds depreciation, the company is investing in growth — building new capacity beyond what's needed to maintain current operations. When depreciation exceeds CapEx, the company may be underinvesting — running down its asset base without adequate replacement, which can lead to future problems.

It Affects Valuation

In the owner earnings formula — net income plus D&A minus CapEx — depreciation plays a crucial role. Adding it back acknowledges that it's not a real cash cost. Subtracting CapEx captures the actual cash needed to maintain the business. The net of these two adjustments reveals the true cash-generating power of the business.

For asset-light businesses (software, services), depreciation is small and the adjustment doesn't move the needle much. For asset-heavy businesses (manufacturers, telecoms, utilities), depreciation can be enormous — often several billion dollars — making the adjustment critical for accurate valuation.

Depreciation Policies Vary

Companies have discretion in how they depreciate assets — they choose the useful life and the depreciation method (straight-line, accelerated, etc.). A company depreciating a machine over 5 years reports higher annual depreciation than one depreciating an identical machine over 10 years. This choice affects reported earnings without changing cash flow.

This is one reason why comparing net income across companies can be misleading — different depreciation policies produce different earnings figures from identical operations. Cash-flow-based metrics like free cash flow and owner earnings are less susceptible to these accounting choices, which is why quality investors prefer them.