After-Tax Cost of Debt Calculator
Calculate the after-tax cost of debt and the tax shield that interest deductibility creates.
Every figure below is labelled in the currency you pick. Amounts are not converted — enter values in the same currency.
Why debt is cheaper than equity
Interest is deductible against corporation tax while dividends are not, so a 7% loan costs a company paying 21% tax only 5.53% in real terms. That deductibility is much of the reason capital structures contain debt at all, and why changes to interest-deduction rules move corporate behaviour so sharply.
The formula
After-tax cost = interest rate × (1 − tax rate)
Every result on this page comes from this formula. Nothing is rounded until the final display, so figures match a spreadsheet to the cent.
How to use the After-Tax Cost of Debt Calculator
- Fill in each field with your own figures — the defaults are only there as an example.
- The result updates as you type, so there is no button to press.
- Check the breakdown under the main result for the supporting numbers.
- Use the copy button to take the result with you, or share the link to reload the same inputs.
After-Tax Cost of Debt Calculator — frequently asked questions
Is this after-tax cost of debt calculator free to use?
Yes. Every calculator on the site is free, needs no sign-up, and runs entirely in your browser, so your figures never leave your device.
How accurate is the result?
The maths is exact for the formula shown on the page. Accuracy in the real world depends on your inputs and on assumptions the formula cannot see, so treat the output as a well-grounded estimate rather than a quote.
Can I use it on my phone?
Yes. The page is responsive, weighs a few kilobytes and works offline once loaded, so it behaves the same on a phone as on a desktop.
What people search for
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About this calculator
Written and reviewed by The Samsung Calculator editorial team. Every calculator is written against a published formula, reviewed against at least one independent reference implementation, and dated when it changes.
Last reviewed August 19, 2026 · Calculation runs client-side · No data collected · Report an error