Equity Forms › E-File Form 3921 Online for 2025 Tax Year

At a Glance
E-filing Form 3921 is required for corporations submitting 10 or more information returns. BoomTax is an IRS authorized e-file provider that supports bulk upload via Excel or CSV for companies with many ISO exercises. The platform validates data before submission and transmits forms securely through the IRS FIRE system. Corrections can be filed through the same platform if errors are discovered after submission.

E-File Form 3921 with BoomTax

BoomTax is an IRS-authorized e-file provider for Form 3921. Our platform is designed for corporations, stock plan administrators, and third-party service providers who need to report Incentive Stock Option exercises.

Why E-File Form 3921?

  • IRS requirement: Electronic filing is mandatory for 10 or more returns
  • Faster processing: E-filed returns are processed more quickly
  • Built-in validation: Catch errors before submission
  • Instant confirmation: Receive acknowledgment from the IRS

What You Need to E-File

To e-file Form 3921 with BoomTax, you will need:

  • Corporation information: Name, address, and EIN
  • Employee information: Name, address, and SSN
  • Option exercise data:
    • Box 1: Date option was granted
    • Box 2: Date option was exercised
    • Box 3: Exercise price per share
    • Box 4: Fair market value per share on exercise date
    • Box 5: Number of shares transferred

For details, see our What is Form 3921 guide.

How BoomTax Works

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

We walk you through the process with no complicated jargon. You can also live chat with a real person as you work on your filing for hands-on help.

E-File & Mail Employee Copies

Once your data is loaded, you can e-file and distribute employee copies in minutes.

Bulk Filing for Stock Plan Administrators

Companies with many ISO exercises can upload data in bulk via Excel or CSV. BoomTax validates your data and transmits it securely to the IRS through the FIRE system.

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

External Resources

Frequently Asked Questions About E-Filing Form 3921

Yes, BoomTax supports filing both Form 3921 (ISO exercises) and Form 3922 (ESPP transfers) in the same submission through the FIRE system. This is convenient for companies that offer both types of equity compensation.

You can file a corrected Form 3921 through BoomTax. Submit a new form with the correct information marked as a correction. The IRS will match it to the original filing using the employee's SSN and exercise date. You should also provide a corrected copy to the employee.

File a separate Form 3921 for each exercise. If an employee exercised options on different dates, or exercised options from different grants on the same date, each exercise requires its own form. BoomTax handles bulk uploads so you can file multiple forms per employee efficiently.

Ken Ham
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Ken Ham
Founder at BoomTax
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Passionate about making tax compliance simple so businesses can focus on what matters.

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