After-Tax Interest Yield CalculatorFree online financial calculator — instant results, no sign-up
Estimate retained taxable interest and yield using a constant applicable tax rate.
Estimates only, based on the inputs and assumptions shown. This is not financial, investment, tax, or legal advice. Prices, rates and local rules may change; crypto scenarios do not predict returns. Confirm important decisions with a qualified professional.
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About the After-Tax Interest Yield Calculator
The After-Tax Interest Yield Calculator estimates how much annual taxable interest you retain after applying a constant tax rate. It uses your principal, annual interest yield, and applicable interest tax rate to show gross interest, estimated interest tax, after-tax interest, and after-tax yield.
- Principal ($)
- The amount invested or deposited, expressed in dollars, with a default of $20,000.
- Annual interest yield (%)
- The annual interest earned as a percentage of principal before tax, with a default of 5%.
- Applicable interest tax rate (%)
- The constant percentage applied to taxable interest to estimate tax, with a default of 24%.
Formula and method
G = P × (r / 100); T = G × (t / 100); A = G − T = P × (r / 100) × (1 − t / 100); y = r × (1 − t / 100). With the defaults: G = 20000 × 0.05 = $1,000.00; T = 1000 × 0.24 = $240.00; A = 1000 − 240 = $760.00; y = 5 × 0.76 = 3.8%.
- PPrincipal in dollars.
- rAnnual interest yield entered as a percentage, such as 5 for 5%.
- tApplicable interest tax rate entered as a percentage, such as 24 for 24%.
- GGross annual interest in dollars, before tax.
- TEstimated annual tax on the interest, in dollars.
- AAfter-tax annual interest retained, in dollars.
- yAfter-tax annual yield expressed as a percentage of principal.
Convert the annual interest yield and tax rate from percentages to decimals. Multiply principal by the annual yield to estimate gross annual interest, then multiply that interest by the tax rate to estimate tax. Subtract estimated tax from gross interest to find retained interest. Reduce the annual yield by the same tax factor to obtain the after-tax yield.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Principal20000 $
- Annual interest yield5 %
- Applicable interest tax rate24 %
Results
- Gross annual interest$1,000.00
- Estimated interest tax$240.00
- After-tax annual interest$760.00
- After-tax yield3.8%
How to use the After-Tax Interest Yield Calculator
- 1Enter the principal in dollars; the default is $20,000.
- 2Enter the annual interest yield before tax; the default is 5%.
- 3Enter the tax rate applicable to the interest; the default is 24%.
- 4Review the gross interest, estimated tax, retained interest, and after-tax yield calculated from your inputs.
- 5For the default inputs, confirm gross annual interest of $1,000.00, estimated interest tax of $240.00, after-tax annual interest of $760.00, and after-tax yield of 3.8%.
Reading your result
Gross annual interest is the interest earned before taxes: $1,000.00 with the default inputs. Estimated interest tax is the portion allocated to tax at the entered rate: $240.00. After-tax annual interest is the amount retained after that estimated tax: $760.00, excluding the original principal. After-tax yield expresses retained interest relative to principal: 3.8% annually, rather than the 5% pretax yield.
Limitations
This is a one-year estimate that assumes the full interest amount is taxable at one constant applicable rate and that principal and yield remain unchanged. It does not determine your tax bracket, calculate a tax return, or separately model federal, state, and local taxes. It also excludes fees, inflation, deposits, withdrawals, tax exemptions, and tax-deferred account rules. Compounding is not modeled separately; if you enter an APY, any compounding reflected in that APY is included only through the entered annual yield. Actual retained interest can differ because of tax timing, rate changes, or account-specific rules.
Common questions
Should I enter my marginal tax rate or my overall effective tax rate?+
Use the rate you expect to apply to the interest itself. For additional taxable interest, your marginal rate may be more appropriate than your overall effective rate. The calculator applies your chosen rate to every dollar of interest and does not determine which rate applies.
Why does a 5% interest yield become 3.8% at a 24% tax rate?+
A 24% tax leaves 76% of the interest available to retain. Multiplying 5% by 0.76 gives 3.8%; on $20,000, that means retaining $760.00 of the $1,000.00 gross annual interest.
Can I use an advertised APY as the annual interest yield?+
Yes, if that APY represents the annual return you expect on the entered principal. The calculator uses it directly to estimate annual interest; it does not reconstruct the compounding schedule or account for taxes reducing the balance during the year.
Does the estimated tax apply to my principal as well as my interest?+
No. The tax calculation applies only to gross annual interest. With the defaults, the 24% rate is applied to $1,000.00 of interest, producing $240.00 of estimated tax; it is not applied to the $20,000 principal.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
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Results are estimates for informational purposes and are not financial, medical or legal advice.