Debt is not automatically bad. Used carefully, it can fund growth that would otherwise take years, buy equipment that pays for itself, or smooth out seasonal swings in cash. But how much a business borrows, and why, often says more about its underlying strength than its profits do.
Warren Buffett and the Interpretation of Financial Statements treats debt as one of the clearest signals of whether a business has a durable competitive advantage. The logic is simple: a business with strong, consistent earnings usually generates enough cash to fund itself. A business that must keep borrowing often cannot. This article explains the measures the book uses, works through examples, looks at why debt behaves the way it does, and draws out what it means for anyone deciding whether and how to borrow.
Why debt is a signal, not just a cost
Interest is an expense like any other, but debt carries information that most expenses do not.
A business borrows for one of a few reasons: to buy assets, to fund growth, to cover a shortfall in cash, or to pay for an acquisition. Each reason tells a different story. Borrowing to buy a machine that will pay for itself in three years is a deliberate investment. Borrowing because customers are paying slowly and suppliers need paying is a symptom. Borrowing every year, simply to keep operating, suggests a business that consumes more cash than it produces.
Businesses with durable advantages tend to generate more cash than they need. Their margins are high, their capital needs modest and their earnings steady. Debt, for them, is usually a choice rather than a necessity. That is why the book treats low debt as one of the fingerprints of a strong business.
Debt amplifies whatever is already there
Debt is often described as leverage, and the word is accurate. A lever magnifies force in both directions.
Consider an illustrative business that buys an asset for $1 million, half with its own money and half with a loan at 8% interest. If the asset earns 15% a year, the owner earns $150,000 minus $40,000 interest, or $110,000 on their $500,000: a 22% return. Leverage has improved the result.
Now suppose the asset earns only 4%. The owner earns $40,000 minus $40,000 interest: nothing. If it earns 2%, the owner loses money while the lender is still paid in full.
| Asset return | Earnings | Interest | Owner’s return on $500,000 |
|---|---|---|---|
| 15% | $150,000 | $40,000 | 22% |
| 8% | $80,000 | $40,000 | 8% |
| 4% | $40,000 | $40,000 | 0% |
| 2% | $20,000 | $40,000 | −4% |
Debt makes good outcomes better and bad outcomes worse. A business with steady, predictable earnings can use it safely. A business whose earnings swing widely, as most businesses without an advantage do, finds that debt turns bad years into dangerous ones.
Interest as a share of operating profit
The first place to look is the income statement. Compare interest expense with operating profit (earnings before interest and tax).
The book suggests that businesses with durable advantages typically pay out less than about 15% of operating profit in interest. In fiercely competitive, capital-hungry industries the figure is often far higher, and in difficult years it can exceed operating profit entirely, meaning the business cannot cover its interest from its own earnings.
The inverse of this ratio is often called interest cover: operating profit divided by interest. An interest cover of 10 means operating profit is ten times the interest bill. Below about 2 or 3, small falls in profit can quickly threaten the ability to pay. Lenders watch this measure closely, and loan agreements often require it to stay above a set level.
There is an important exception. Banks and lenders borrow as their core business, so interest is effectively their cost of goods, not a sign of weakness. Comparisons only make sense within an industry.
Long-term debt measured in years of earnings
The second check uses the balance sheet. Take long-term debt and divide it by annual net earnings. The result is roughly how many years of profit it would take to repay everything.
According to the authors, the businesses Buffett favoured could typically repay their long-term debt within three or four years of net earnings, and some could do it in one. Businesses that could not repay their debt even with a decade of profits were, in their view, structurally weak.
This measure is a useful reality check, because it translates an abstract balance-sheet number into a question anyone can understand: if the business stopped borrowing today, how long would it take to be free of debt?
The book adds a caution. A strong business sometimes carries heavy debt because it was bought with borrowed money in a leveraged buyout. In that case the debt reflects the purchase, not the business, and needs to be read differently. The underlying business may be excellent; the question is whether it can carry the debt its new owners loaded onto it.
Debt against equity
A third measure is total liabilities compared with shareholders’ equity, sometimes called a debt-to-equity or liabilities-to-equity ratio. The book suggests that a ratio below about 0.8 is a good sign, with lower being better.
It adds a subtlety. Companies that buy back large amounts of their own stock reduce their reported equity, which makes the ratio look worse than it really is. The authors adjust for this by adding the value of repurchased shares back to equity before calculating the ratio. Without that adjustment, some of the strongest businesses would appear heavily indebted when they are not.
A worked comparison
Here are two illustrative businesses, each with operating profit of $10 million.
| Business A | Business B | |
|---|---|---|
| Operating profit | $10.0m | $10.0m |
| Interest expense | $0.8m | $4.5m |
| Interest as share of operating profit | 8% | 45% |
| Net earnings | $6.4m | $3.9m |
| Long-term debt | $15m | $90m |
| Years of earnings to repay | about 2.3 | about 23 |
Business A could clear its long-term debt in a little over two years of earnings. Its interest bill barely dents its profit. Business B pays nearly half its operating profit to lenders and would need more than two decades of earnings to repay its debt. If its operating profit fell by half in a bad year, it would struggle to pay interest at all.
On the surface both businesses are profitable. Underneath, one stands on its own and the other depends on its lenders’ continued goodwill.
The particular danger of short-term borrowing
The book also highlights a risk that has brought down many financial institutions: borrowing short-term to fund long-term commitments.
It looks profitable at first. Short-term money is often cheaper, so a lender can borrow short and lend long at a higher rate. But when short-term rates rise, or lenders refuse to roll the debt over, the business must refinance at a worse rate or find cash it does not have. A mismatch that looked clever for years can become fatal in weeks.
The same risk applies outside banking. A business that funds a new factory with a short-term overdraft, or finances long-term contracts with debt that must be renewed annually, is exposed whenever credit tightens. And credit tends to tighten exactly when business conditions are worst.
A business with a durable advantage rarely depends on this kind of funding. It does not need to.
Hidden and less obvious obligations
Not all commitments are labelled “debt”. When reading a balance sheet, it is worth looking for:
- Lease liabilities: under current accounting standards most leases appear on the balance sheet, but they are sometimes overlooked when people think about borrowing.
- Supplier finance arrangements: some businesses extend their payment terms through financing arrangements that behave like debt.
- Guarantees and contingent liabilities: promises to pay if something goes wrong, disclosed in the notes.
- Provisions: amounts set aside for obligations such as warranties, restoration or employee entitlements.
None of these is necessarily a problem, but together they show the full extent of what the business owes.
How lenders think
It helps to understand debt from the lender’s side. A bank lending to a small business typically looks at:
- cash flow: can the business pay interest and repayments from its operations?
- security: what assets back the loan if things go wrong?
- history: how has the business performed over several years?
- character: are the owners reliable, and do they have their own money at risk?
Lenders often lend against assets and personal guarantees rather than against the business’s true earning power. That means a lender may offer more than the business can comfortably repay, particularly to owners who have property to guarantee the loan. The amount a bank will lend is not a measure of how much a business should borrow.
What this means for building a business
For a new business, debt decisions are often made under pressure, and they tend to stick. A few principles follow from the book’s lens.
Let the business prove it can fund itself before it borrows to grow. Debt amplifies whatever is already there, good or bad. Borrowing to scale an unproven model scales the risk as well.
Match the term of the debt to the life of the asset. A five-year machine suits a five-year loan. Short-term borrowing for long-term investments creates refinancing risk.
Measure capacity in years of earnings, not in what lenders will offer. Ask how long it would take to repay from realistic earnings, including a bad year.
Treat a rising interest bill as information. It usually means the business is consuming more cash than it produces, and that deserves an explanation before more borrowing.
Keep a buffer. Undrawn facilities and cash reserves give room to handle surprises without emergency borrowing on poor terms.
Be cautious with personal guarantees. Many small-business loans require them, putting the owner’s home or savings at risk. Understand exactly what is being guaranteed.
The goal is not zero debt at any cost. It is to build a business strong enough that debt is a choice rather than a necessity.
A worked example
A small food manufacturer wins a large supermarket contract. This is an illustration.
To meet the order, it needs new packaging equipment and enough stock and working capital to cover the supermarket’s 60-day payment terms. The owners borrow heavily: an equipment loan plus a large overdraft. For the first year, all goes well.
In the second year, the supermarket renegotiates prices downward and extends its payment terms. Margins fall, the overdraft rises to cover the longer wait for payment, and interest consumes most of the operating profit. The business is now working mainly for its lender.
The owners restructure: they convert part of the overdraft to a term loan matched to the equipment’s life, diversify into smaller retailers and food service customers with better terms, and slow their growth until earnings rebuild. Within two years interest falls back to a modest share of operating profit.
The lesson is not that the contract was a mistake. It is that the debt was sized for the best case, and the business had little margin for the ordinary pressures of a large customer relationship.
Common mistakes
Borrowing because credit is available. Availability is not affordability.
Funding long-term needs with short-term debt. It creates refinancing risk at the worst possible time.
Ignoring leases and other obligations. They are commitments too.
Sizing debt for the best case. Plan for an ordinary bad year, not a perfect one.
Using debt to cover persistent cash shortfalls. It delays the problem while making it larger.
Questions to ask
- What share of operating profit goes to interest, and is it rising?
- How many years of earnings would repay the long-term debt?
- How much debt is short-term, and could it be renewed in a downturn?
- What other obligations sit in the notes?
- For your own business: if earnings fell by a third next year, could you still comfortably meet your repayments?
Bringing it together
Debt is a tool, and like any tool it reflects the hand that uses it. Businesses with durable advantages usually borrow little, pay small interest bills relative to their profits and could repay their debts within a few years of earnings. Businesses that depend on borrowing, especially short-term borrowing, are often revealing that they cannot fund themselves.
For anyone building a business, the lesson is to borrow from strength rather than from necessity: prove the model, match debt to the assets it funds, keep a buffer and treat a rising interest bill as a warning light worth investigating.
Source: Mary Buffett and David Clark, Warren Buffett and the Interpretation of Financial Statements (2008). Figures in this article are illustrations, not data. This article is general information, not financial, lending or investment advice.
