This calculator helps you determine the true after-tax cost of borrowing money for personal loans, credit cards, or mortgages.
Understanding your actual debt cost is essential for making smart budgeting decisions and prioritizing which debts to pay off first.
It accounts for tax deductions on interest, giving you a realistic picture of what your debt really costs you.
💰 Cost of Debt Calculator
Tip: Higher tax brackets benefit more from tax-deductible debt. Always compare the After-Tax Cost when choosing loans.
How to Use This Tool
Enter your loan's interest rate (APR) and your current tax bracket percentage. Select how often interest compounds (monthly is standard for most loans). If you want to see specific dollar amounts, enter your loan balance. The tool will calculate your true borrowing cost after tax savings.
Formula and Logic
Effective Annual Rate (EAR): This shows the real cost when compounding is considered. Formula: (1 + r/n)^n - 1, where r is your nominal rate and n is compounding periods per year.
After-Tax Cost: For tax-deductible debt: Nominal Rate × (1 - Tax Rate). This is your actual cost after IRS deductions. Non-deductible debt uses the full nominal rate.
Practical Notes
- Tax Bracket Impact: Higher tax brackets reduce your after-tax cost more significantly. A 6% loan costs very different amounts to someone in the 12% bracket versus the 32% bracket.
- Compounding Matters: A loan with daily compounding costs more than one with annual compounding, even at the same APR. Always check the EAR.
- Deduction Rules: Mortgage interest and business loans are generally deductible. Personal loans and credit cards are not. Credit card interest is effectively paid with after-tax dollars.
- Budgeting Strategy: Focus extra payments on debts with the highest after-tax costs first. This saves the most money over time.
Why This Tool Is Useful
Most people only look at the interest rate, but that's not the full picture. Your tax bracket and compounding frequency significantly change the true cost. This calculator helps you compare different loan options apples-to-apples and make smarter financial decisions about debt consolidation, refinancing, or payoff strategies.
Frequently Asked Questions
What if I don't know my exact tax rate?
Use your marginal tax bracket (the tax rate on your next dollar of income). You can find this on current IRS tax tables or by checking your last paystub's year-to-date tax withholding. If you're unsure, 22% is a common middle-class rate.
Does this work for credit cards?
Yes, but credit card interest is NOT tax deductible. Select "Non-Deductible" for the debt type. This will show you the full impact of high-interest personal debt, which is often much higher than people realize.
Why is my after-tax cost lower than the rate I see on my statement?
If you selected a tax-deductible option (like mortgage or business debt), the after-tax cost is lower because you get to deduct the interest from your taxable income. The government effectively subsidizes part of your interest payment through tax savings.
Additional Guidance
Remember that tax laws change frequently. Always verify current deduction rules with a tax professional. For business debts, keep detailed records of interest payments. Consider the after-tax cost when deciding between paying off debt versus investing. If your after-tax debt cost is 4%, but you can earn 7% investing, mathematically it makes sense to invest. However, paying off debt also reduces risk and improves cash flow.