Equity Forms › What is Form 3921? Incentive Stock Option Exercise Reporting
At a Glance
Understanding IRS Form 3921
Form 3921 (Exercise of an Incentive Stock Option Under Section 422(b)) is used to report the exercise of Incentive Stock Options (ISOs). Corporations that transfer stock to employees pursuant to an ISO must file this form for each exercise during the tax year.
The information on Form 3921 helps employees determine the tax treatment of their stock options and calculate any potential Alternative Minimum Tax (AMT) liability.
Who Must File Form 3921?
Form 3921 must be filed by corporations that:
- Grant Incentive Stock Options (ISOs) under IRC Section 422(b)
- Transfer stock to employees upon exercise of those options
The form must be filed for each ISO exercise, regardless of whether the employee holds or sells the stock after exercise.
Form 3921 Box Breakdown
| Box | Description |
|---|---|
| 1 | Date option was granted |
| 2 | Date option was exercised |
| 3 | Exercise price per share |
| 4 | Fair market value per share on exercise date |
| 5 | Number of shares transferred |
Incentive Stock Options Explained
ISOs are a type of employee stock option that can qualify for favorable tax treatment if certain requirements are met:
- Holding period: Stock must be held for at least 2 years from grant date and 1 year from exercise date
- Employment requirement: Employee must remain employed from grant until 3 months before exercise
- Annual limit: Only $100,000 of ISOs (based on grant date FMV) can become exercisable in any year
Tax Treatment of ISOs
When properly exercised and held, ISOs can receive favorable tax treatment:
- No regular income tax at exercise: Unlike non-qualified options, ISO exercises are not taxed as ordinary income
- Capital gains treatment: If holding period requirements are met, gains are taxed as long-term capital gains
- AMT consideration: The "spread" (FMV minus exercise price) at exercise is an AMT preference item
Important: If holding period requirements are not met (disqualifying disposition), the spread at exercise becomes ordinary income.
E-File Form 3921 with BoomTax
E-file your Form 3921 with the IRS using BoomTax. Our platform is designed for corporations and stock plan administrators who need to file these forms in bulk.
Import Your Form 3921 Data
You can import your data as Excel, XML, or use files from popular payroll providers like QuickBooks, UKG, ADP, and many more.
Step-By-Step Wizard
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E-File & Mail Employee Copies
Once your data is loaded, you can e-file and distribute employee copies in minutes.
Filing Deadlines
- Employee copy: January 31
- IRS filing (paper): February 28
- IRS filing (electronic): March 31
For details, see our Form 3921 due date guide.
Related Forms
- Form 3922: Reports ESPP stock transfers
External Resources
ISO Qualifying Disposition Timeline
Grant Date
ISO option granted to employee
Exercise Date
Employee exercises option (Form 3921 filed)
1+ Year After Exercise
Holding period #1
2+ Years After Grant
Qualifying disposition = LTCG
Frequently Asked Questions About Form 3921
Incentive Stock Options (ISOs) can receive favorable tax treatment if holding requirements are met - no ordinary income at exercise and long-term capital gains on sale. Non-qualified stock options (NQSOs) are taxed as ordinary income at exercise on the spread between exercise price and FMV. Only ISO exercises require Form 3921; NQSOs are reported on Form W-2.
The Alternative Minimum Tax (AMT) is a parallel tax system with fewer deductions. When you exercise an ISO, the "spread" (FMV minus exercise price) is an AMT preference item. This means you may owe AMT in the year of exercise even though you don't owe regular income tax. Form 3921 provides the data needed for AMT calculations on Form 6251.
A disqualifying disposition occurs when you sell ISO stock before meeting both holding requirements (2 years from grant AND 1 year from exercise). When this happens, the spread at exercise becomes ordinary income (reported on W-2), and you lose the favorable capital gains treatment. The employer must report this as compensation.
Yes, Form 3921 must be filed for every ISO exercise, regardless of whether the employee holds or immediately sells the stock. A same-day sale is a disqualifying disposition, but the exercise still requires Form 3921. The employer will also need to report the ordinary income on the employee's W-2.
For publicly traded stock, the FMV is typically the closing price on the exercise date, or an average of high and low prices. For private company stock, FMV must be determined by a 409A valuation - a formal appraisal conducted by independent experts, usually within 12 months of the exercise date.
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BoomTax and its affiliates do not provide tax, legal, or accounting advice. This material has been prepared for informational purposes only, and is not intended to provide, and should not be relied on for, tax, legal, or accounting advice. You should consult your own tax, legal, and accounting advisors prior to engaging in any transaction.