What is the tax shield on debt?

It is the tax saved because interest payments are deductible. A business paying $10,000 in interest at a 25% effective tax rate saves $2,500 in tax. That saving is the shield. The after-tax cost of debt includes that saving in the final number.

What's the difference between pre-tax and after-tax cost of debt?

The pre-tax cost of debt is the actual interest rate on the loan. The after-tax cost of debt os interest rate after accounting for tax savings. It’s adjusted to reflect the deduction. The size of that adjustment depends on the effective tax rate. A higher tax rate produces a larger reduction and a lower after-tax cost.

How does the after-tax cost of debt affect my WACC?

Weighted average cost of capital (WACC) includes the cost of debt and the cost of equity. Debt cost is taken after tax because interest reduces taxable profit. This lowers WACC. If tax is not considered and the full interest rate is used, WACC becomes higher. This can make good investments look less attractive.

How is after-tax cost of debt different from after-tax cost of equity?

When borrowing money, a portion of the interest can be deducted for tax purposes, which keeps the cost of borrowing lower. On the other side, equity does not provide any tax deduction. Thus, the after-tax cost of debt is usually lower than the cost of equity..

After-Tax Cost of Debt Calculator: Measure Real Debt Costs

What is the after-tax cost of debt?

Borrowing is expensive. When businesses borrow money, they pay interest expense. However, businesses can also deduct their interest expense from their taxable income, which reduces their tax bill.

To calculate the after-tax cost of just borrowing money, multiply the loan’s interest rate by (1- tax rate).

For example:

A $100,000 loan at 9% interest with a tax rate of 25%

= 9% x (1 –0.25) = 6.75% aftertax

So while the lender is receiving 9% interest, the business effectively pays an after-tax borrowing cost of 6.75%.

The interest rate alone may not fully encompass the total dollar amount a business must repay. Take Two different companies that have identical loan amounts yet have different tax rates will pay different borrowings costs based solely on their tax situations. The after-tax cost provides the most accurate amounts for comparison.

How to use this calculator?

Enter three inputs to get the result:

1. Debt cost

The annual interest rate on the loan. Use the APR, not the monthly rate. If there are multiple loans, calculate a weighted average based on outstanding balances.

2. Net income

Used to calculate the effective tax rate. Take this from the most recent full-year income statement.

3. Pre-tax income

Earnings before tax for the same period. The calculator uses this with taxes paid to find the effective tax rate and adjust the debt cost.

Do not use the marginal rate. It can make the after-tax cost look lower than it actually is.

Why the after-tax cost of debt matters for business decisions?

When a business takes a loan or compares funding options, the key question is the real cost. The after-tax cost gives that answer.

Interest on loans can be deducted from income, but payments to investors cannot. This makes debt cheaper than it looks if tax is considered. Ignoring this can lead to wrong decisions.

The after-tax cost is also used in WACC (Weighted Average Cost of Capital), which is the minimum return a business needs to justify its funding. If a return is lower than WACC, the business loses value.

For example, a 10% loan with a 30% tax rate actually costs 7%. This difference can change whether a decision makes sense.

After Tax Cost Debt Calculator