Cost of Debt Explained: Formula, Factors & Examples

The cost of debt is the effective interest rate a company pays on its borrowed capital, including loans, bonds, or other financing. It represents the financial cost of using debt to fund operations, expansions, or investments and is a critical piece of a business’s overall capital structure. For businesses, the cost of debt plays a significant role in evaluating financial health and determining whether new debt aligns with long-term goals.

Because interest payments are typically tax-deductible, calculating the cost of debt isn’t as simple as looking at an annual percentage rate (APR). You need to look at the after-tax cost to have a more accurate view of debt’s true impact. In this article, we’ll explore the formula for the cost of debt, demonstrate its calculation with examples, and examine factors that influence it.

How to Calculate the Cost of Debt

The cost of debt measures the effective interest rate a company pays on its borrowing, adjusted for the tax benefits of deductible interest expenses.

The formula for calculating the after-tax cost of debt is:

After-Tax Cost of Debt = (Total Interest Expense / Total Debt) x (1 – Tax Rate)

This formula accounts for the tax shield created by interest payments, providing a clearer view of the true cost of borrowing. The formula encompasses:

• Total Interest Expense: The total amount of interest a company pays on its debt during a given period. For example, interest payments on loans, bonds, or credit facilities would all be included. It represents the direct financial cost of servicing the debt.
• Total Debt: Total debt includes all current (short-term) and non-current (long-term) liabilities on the company’s balance sheet. This figure reflects the overall borrowing burden a business is carrying.
• Tax Rate: The corporate tax rate determines how much a company can deduct from its taxable income for interest expenses. For example, with a 30% tax rate, the after-tax cost of debt would reflect a 70% net borrowing cost.

You can use this formula to calculate pre- or after-tax cost of debt. Calculating after-tax debt is likely more relevant for decision-making.

Step-by-Step Example of Calculating Cost of Debt

To better understand how to calculate the cost of debt, let’s walk through an example. A company has the following financial details:

• Total Debt: $1,000,000
• Annual Interest Expense: $50,000
• Corporate Tax Rate: 30%

Let’s calculate both the pre-tax and after-tax cost of debt.

Step 1: Calculate the Pre-Tax Cost of Debt

The pre-tax cost of debt is determined by dividing the total interest expense by the total debt:

Pre-Tax Cost of Debt = Total Interest Expense / Total Debt

In this case:

Pre-Tax Cost of Debt = $50,000 / $1,000,000 = 0.05 or 5%

The pre-tax cost of debt for this company is 5%.

Step 2: Calculate the After-Tax Cost of Debt

To calculate the after-tax cost of debt, adjust the pre-tax cost by the tax rate:

After-Tax Cost of Debt = Pre-Tax Cost of Debt × (1 – Tax Rate)

In this example:

After-Tax Cost of Debt = 5% × (1 – 0.30) = 5% × 0.70 = 3.5%

The after-tax cost of debt for this company is 3.5%.

Step 3: Interpret the Results

The after-tax cost of debt (3.5%) represents the actual expense the company incurs for borrowing after factoring in the tax benefits of interest deductions. This lower rate reflects the financial advantage of using debt over equity in some cases, especially when interest expenses are tax-deductible.

By understanding and calculating the cost of debt, businesses can evaluate the expense of their borrowing and make informed decisions about whether taking on new debt aligns with their financial strategy.

Factors That Impact Cost of Debt

Several factors influence a company’s cost of debt, shaping the overall expense of borrowing. Understanding these variables can help businesses manage their financing more effectively and secure favorable terms.

1. Creditworthiness and Credit Ratings

The stronger a company’s credit profile, the lower its cost of debt. Just like individuals, businesses have credit scores. Higher credit scores indicate lower risk for lenders, often leading to reduced interest rates. Low credit scores are seen as riskier, so borrowers may face higher costs.

Brennan Kolar, founder of Atlas CPA Index, says “A business with a 720+ credit score, three years of operating history, and $500,000 in annual revenue is going to get a very different rate than one with a 620 score that’s been open for 14 months. Lenders want to do everything they can to ensure that they are lending to reliable customers, which is why they incentivize these reliability factors by offering lower costs of debt.”

Your business credit score is based on many factors, including payment history and credit utilization, so it’s important to pay debts and vendors on time to lower your cost of debt. You can check your credit score for free from each of the business credit bureaus.

2. Prevailing Interest Rates and Market Conditions

Macroeconomic trends heavily influence borrowing costs. When central banks lower interest rates to stimulate economic growth, businesses benefit from cheaper debt financing. Conversely, in periods of monetary tightening or inflation, interest rates rise, increasing the cost of borrowing.

For instance, during an economic boom, rising demand for loans may push interest rates higher, whereas during a downturn, central banks often reduce rates to encourage borrowing and investment. Businesses need to monitor market conditions closely to time their debt financing decisions.

3. Type of Debt

The nature of the debt itself affects its cost. Secured loans, which are backed by collateral, generally offer lower interest rates because lenders face reduced risk. Kolar says, “A loan backed by real estate will carry a lower cost of debt than an unsecured line of credit, even for the same borrower, because the lender’s recovery position is stronger if something goes wrong.”

Additionally, fixed-rate loans provide predictable payments but can be higher than variable-rate loans in low-rate environments. However, variable-rate loans come with the risk of increasing costs if interest rates rise.

4. Debt Maturity and Term Length

The length of the borrowing term significantly influences the interest rate and cost of debt. Short-term loans typically come with lower rates but may require frequent refinancing, adding administrative and potential interest rate risks. Long-term loans, while offering stability, often come with higher interest rates to account for the increased uncertainty over extended periods.

You also have to consider the total cost of the loan. You might have a lower interest rate on a 10-year loan than a 5-year loan, but five more years of payments will undoubtedly increase the overall cost of debt. Is it worth the lower monthly payment if you end up paying thousands of more overall? That’s up to you to determine.

5. Company Size and Industry

Larger, established companies often have access to lower borrowing rates because they’re perceived as less risky compared to smaller businesses or startups. Additionally, the industry a company operates in can impact borrowing costs. For instance, businesses in highly volatile or cyclical industries, like technology or construction, may face higher interest rates than companies in stable industries such as utilities.

6. Tax Rate and Deductibility of Interest

The corporate tax rate directly affects the after-tax cost of debt. Since interest payments are typically tax-deductible, a higher tax rate increases the value of this deduction, lowering the effective cost of debt. On the other hand, reductions in corporate tax rates, such as those enacted by tax reforms, can lead to a higher after-tax borrowing cost.

For example, if a company pays $50,000 in annual interest and has a tax rate of 30%, the after-tax cost is reduced to $35,000. If the tax rate drops to 20%, the after-tax cost rises to $40,000, increasing the effective cost of debt.

7. Fees and Markups

Don’t just look at an interest rate. A loan’s APR accounts for its total annual borrowing costs, including fees or penalties. Kolar says, “A lot of business owners focus on the interest rate alone and don’t account for origination fees, closing costs, or prepayment penalties, all of which raise the effective cost of debt above the stated APR.” Understanding these additional costs can help you better manage the cost of debt.

Cost of Debt vs. Cost of Equity

While the cost of debt reflects the expense of borrowing funds, the cost of equity represents the returns investors expect in exchange for financing the business. Together, these components form the basis of a company’s weighted average cost of capital (WACC), which measures the overall cost of financing operations.

Definition and Calculation

The cost of debt is calculated as the effective interest rate on borrowed funds, adjusted for tax benefits. It is often easier to determine because interest payments are clearly defined in loan agreements or bond terms.

In contrast, the cost of equity represents the expected return required by investors for taking on the risk of holding equity. This is more complex to calculate and often relies on financial models like the Capital Asset Pricing Model (CAPM). Unlike debt, equity does not have fixed payments, which makes its cost more variable.

Tax Implications

Debt financing provides a tax advantage, as interest expenses are tax-deductible. This reduces the after-tax cost of debt, making it more affordable for companies. In comparison, dividends paid to shareholders are not tax-deductible, which increases the effective cost of equity financing.

Risk and Obligation

Debt financing involves fixed repayment obligations, which can create financial strain if a company’s cash flow declines. Missing payments can lead to penalties or even bankruptcy.

Equity financing, on the other hand, does not require repayment and offers greater flexibility in times of financial uncertainty. However, it dilutes ownership, as equity investors gain a stake in the business and may seek a role in decision-making.

Cost and Accessibility

Debt is typically less expensive than equity, especially for businesses with strong credit ratings. Lenders assume lower risk compared to equity investors, as debt is prioritized for repayment in case of liquidation. However, excessive reliance on debt can increase financial risk.

Equity financing may be more accessible for startups or businesses with limited credit history. While it eliminates repayment obligations, the long-term cost of equity is often higher due to investors’ expectations for significant returns.

How They Work Together

The cost of debt and cost of equity are combined in the WACC formula, providing a comprehensive view of a company’s financing costs. A lower WACC indicates more efficient financing, enhancing profitability and competitiveness.

While debt offers tax advantages and lower upfront costs, it carries the risk of fixed repayment obligations. Equity, though more expensive, provides flexibility and avoids the financial pressure of mandatory payments. Striking the right balance between debt and equity is crucial for sustainable growth.