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The Global Insight

What decreases after-tax cost of debt?

Author

Mia Phillips

Updated on February 06, 2026

Cost of Debt After Taxes The after-tax cost of debt is the interest paid on debt less any income tax savings due to deductible interest expenses. To calculate the after-tax cost of debt, subtract a company’s effective tax rate from 1, and multiply the difference by its cost of debt.

Why cost of debt is lower?

Well, the answer is that cost of debt is cheaper than cost of equity. As debt is less risky than equity, the required return needed to compensate the debt investors is less than the required return needed to compensate the equity investors.

Can the cost of debt be negative?

Cost of debt is what the company pays to its debtholders. It cannot be negative either. It can be 0 but cannot be negative. Interest expense is negative when you pay more interest than you get paid.

Why is after-tax cost of debt important?

The primary benefit of calculating the after-tax cost of debt is knowing how much a business can save on its taxes due to the interest it paid over the year. This means businesses need to know their effective tax rate to understand their total cost of debt. Calculating the effective tax rate for a business is easy.

Why do we use the after-tax cost of debt in WACC?

The reason WHY we use after-tax cost of debt in calculating the WACC because we are interested in maximizing the value of the firm ‘ s stock, and the stock price depends on after-tax cash flows NOT before-tax cash flows. That is why we adjust the interest rate downward due to debt ‘ s preferential tax treatment.

Is WACC before or after-tax?

WACC is the average after-tax cost of a company’s various capital sources, including common stock, preferred stock, bonds, and any other long-term debt. In other words, WACC is the average rate a company expects to pay to finance its assets.

Which is costly debt or equity?

The capital structure of a business is usually composed of both equity and debt. The dividend that is paid off to the shareholders is the equity cost. In the case of debts, the company pays the loan and the interests. The cost of borrowing is the cost of payment of the debt instruments.

What does a WACC of 3% mean?

In theory, WACC represents the expense of raising one additional dollar of money. For example, a WACC of 3.7% means the company must pay its investors an average of $0.037 in return for every $1 in extra funding. Because shareholders expect a return of 6% on their investment, the cost of equity is 6%.

Why do we use after-tax cost of debt in WACC?

Why is WACC after tax?

What is the tax rate for WACC?

The tax shield Notice in the WACC formula above that the cost of debt is adjusted lower to reflect the company’s tax rate. For example, a company with a 10% cost of debt and a 25% tax rate has a cost of debt of 10% x (1-0.25) = 7.5% after the tax adjustment.

Why is debt good for a country?

In the short run, public debt is a good way for countries to get extra funds to invest in their economic growth. Public debt is a safe way for foreigners to invest in a country’s growth by buying government bonds. When used correctly, public debt improves the standard of living in a country.