Free Stock Option Tax Calculator
Estimate a 2024 NSO exercise scenario using historical closing prices and explicit income assumptions. ISO mode shows the spread only; federal or state AMT is not calculated. This is not a current-year calculator or an exercise-date FMV determination.
Exercise price per your option grant
Shares you plan to exercise
Historical date for the 2024 reference calculation
Tax Information
After deductions; exclude this exercise and preferential-rate gains
Flat scenario rate, not a state-law calculation
What the 2024 Scenario Calculates
The tool retrieves a closing price on or before your selected 2024 date, within a ten-day lookback. The positive spread is max(0, reference close minus strike) multiplied by whole shares. Provider prices may be split-adjusted: use share counts and strikes on a consistent basis. This reference is not a substitute for an employer’s exercise-date valuation or tax records.
NSO Calculation Method
For the modeled employee NSO, the spread is treated as added ordinary compensation. Federal tax is the difference between the 2024 bracket calculation with and without that spread. Enter other ordinary taxable income after deductions; deductions and preferential capital-gain rates are not calculated here.
Payroll taxes use separate wage inputs. Social Security applies 6.2% only to the option holder’s remaining 2024 wage base of $168,600. Medicare applies 1.45%; the additional 0.9% uses thresholds of $250,000 jointly, $125,000 separately, or $200,000 otherwise. Joint Medicare wages include both spouses. This is a wage-only scenario, not employer withholding or a computation including self-employment and railroad compensation.
ISO and State-Tax Limits
Qualifying ISO exercise generally does not create regular federal income, but AMT may apply. The calculator does not gather the full return information needed to compute it and therefore displays no ISO tax estimate. A same-year sale can change the AMT adjustment; a future AMT credit is conditional.
The state-rate input is a flat NSO scenario assumption, not a state tax engine. It is not applied to ISO mode. California has separate regular-tax and AMT treatment for ISOs; it is incorrect to treat every California ISO exercise as an NSO.
Using the Result
- Select a supported USD ticker and a date in 2024.
- Enter strike and shares using the same split-adjustment basis as the reference quote.
- For NSOs, enter ordinary taxable income and the two distinct wage amounts, excluding this exercise.
- Inspect the price date and assumptions before comparing scenarios. Exercise does not itself create sale proceeds.
Sources: IRS 2024 tax brackets, SSA 2024 wage base, IRS Additional Medicare Tax, IRS Stock Options, and California stock-option guidelines.
Frequently Asked Questions
Which tax year does this calculator cover?
Only 2024 U.S. employee-option scenarios. The NSO estimate uses 2024 ordinary-income brackets and the $168,600 Social Security wage base. It is not a current-year tax calculator and does not prepare a return.
What does NSO mode calculate?
It treats the positive price spread as additional employee compensation and estimates incremental ordinary federal income tax, employee Social Security and Medicare, plus your flat state-rate assumption. Special grants, vesting, deductions, credits, capital-gain rate interactions, self-employment, and state sourcing are not modeled.
Does ISO mode calculate AMT?
No. It shows the quote-based exercise spread for review. A potential ISO AMT adjustment is not the tax owed. Actual AMT requires the other Form 6251 inputs, regular tax, sale facts, and possible credits. State ISO tax is also not calculated.
Which income values should I enter?
Enter ordinary taxable income after deductions, excluding this option exercise. Separately enter the option holder’s other Social Security wages and the return’s other Medicare wages; for a joint return, Medicare wages include both spouses. Do not substitute taxable income for payroll wages.
Is the historical close the tax fair market value?
Not necessarily. The close on or before your chosen 2024 date is a scenario input. Provider split adjustments, currency, and employer valuation rules can differ from your exercise records. This tool accepts USD-listed securities and cannot determine private-company FMV.
Are the displayed amounts proceeds from a sale?
No sale is modeled. The after-tax spread subtracts the NSO scenario tax from the quoted value minus exercise cost. Actual proceeds require an actual sale price, costs, and the correct tax basis.
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