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IRSOther IRS Forms (2000–3999)

Official form guide

Form 3921: 3921

Form 3921 reports the transfer of stock acquired through an employee's exercise of an incentive stock option (ISO). Employers file it with the IRS and provide a copy to the employee for the tax year the exercise occurred.

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Form Overview

IRS Form 3921 - 3921

Form 3921 reports the transfer of stock acquired through an employee's exercise of an incentive stock option (ISO). Employers file it with the IRS and provide a copy to the employee for the tax year the exercise occurred.

It captures the employee’s name, SSN, date of exercise, number of shares transferred, exercise price, and fair market value on the exercise date.

Risk Radar

Scan points
  • 1A single typo can generate an IRS penalty and delay the employee’s tax filing.
  • 2Wrong employee SSN or name
  • 3Exercise price and FMV swapped
  • 4Missing or late employee copy
  • 5Filing after the Feb 28/March 31 deadline

Plain English

When a worker uses an ISO to buy company shares, the company must tell the IRS how many shares were bought, the price paid, and the fair market value on that day. The employee gets the same info to use on their personal tax return.

Submission Date

  • Filing date: 2026-02-10 16:10:39
  • Preparation window: collect IDs, supporting records, and signatures in advance.
  • Final review: verify names, dates, and required fields before submission.

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Glossary Terms

fair market valuemarket valuefair marketincentiveoccurredoptionmarket

Hover a term to preview the meaning.

What this form is for

  • Use when an employee exercises an Incentive Stock Option.
  • Do not use for non‑qualified stock options or other equity awards.
  • If the transaction is a disqualifying disposition, report on Form 8949 instead.

Form selector

Use this form or another form?

Non‑qualified stock option exercise

Reports transfer of stock under a non‑qualified plan

✓ Verify option type before filing

Form 3922

Stock purchase plan distribution

Reports dividends, not option exercises

✓ Use only for dividend income

Form 1099‑DIV

Deadline or filing window

The employer must file Form 3921 with the IRS by February 28 (paper) or March 31 (electronic) of the year after the exercise. The employee copy must be delivered by January 31 of the same year. Missing these dates can trigger a $50 per‑form penalty.

  • —Number of shares exercised | multiply by exercise price | Total exercise cost | Verify price matches grant documents

Checklist

What you need before filling it out

1

Employee name/SSN

Payroll or HR records · Employee file

⚠ Misspelled name or transposed SSN✕ High
2

Date of exercise

Option agreement or brokerage statement · Transaction log

⚠ Wrong year entered✕ Medium
3

Number of shares

Stock ledger · Option grant schedule

⚠ Off‑by‑one errors✕ Medium
4

Exercise price per share

Grant agreement · Option paperwork

⚠ Swapped with FMV✕ High
5

Fair market value on exercise date

Bloomberg/FactSet or internal valuation · Market data

⚠ Outdated price used✕ High

Before you submit

  1. 1Confirm all ISO exercises for the calendar year are listed.
  2. 2Verify employee name and SSN match IRS records.
  3. 3Check that exercise price and FMV are entered in correct columns.
  4. 4Ensure totals on the summary page match line items.
  5. 5Validate the filing method (paper vs. FIRE) matches volume.
  6. 6Attach required signature on paper forms.
  7. 7Mail to the correct IRS address or upload via FIRE.
  8. 8Send employee copies by Jan 31.
  9. 9Retain a copy of the filed form for at least 7 years.
  10. 10Record the filing confirmation number (electronic) or certified mail receipt.
  11. 11Cross‑check with payroll to ensure no duplicate reporting.

How to file this form

  1. 1Export ISO exercise data from the equity plan system.
  2. 2Map data fields to Form 3921 line items.
  3. 3Enter data into the IRS PDF or electronic upload template.
  4. 4Run a validation check for missing SSNs or dates.
  5. 5Submit via FIRE (if >250 forms) or mail paper copies.
  6. 6Print and sign paper forms if required.
  7. 7Distribute employee copies and file a copy internally.

Known limitations

  1. 1Form does not capture disqualifying disposition details.
  2. 2Only reports ISO exercises, not grants or cancellations.
  3. 3Electronic filing requires a valid Transmitters Control Code (TCC).
  4. 4The form provides no field for state tax withholding.

Field map

Compact field-by-field guide

6 fields

General Info

2 items

Taxpayer Name and TIN

Full legal name and taxpayer identification number (SSN or EIN).

Requiredtext
Address

Current mailing address.

Requiredtext

Details

2 items

Required Information

Complete all applicable sections of this form according to the official IRS instructions.

Requiredtext
Amount (if applicable)

Enter the relevant dollar amount if this form involves tax calculation.

amount

Certification

1 items

Certification Statement

Read and acknowledge any certifications required by this form.

Requiredcheckbox

Signatures

1 items

Signature

Sign and date. Unsigned forms cannot be processed.

Requiredsignature
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Current form status
IRS

Form 3921 for the 2024 tax year is currently in the 2025 filing season. The latest edition is the 2024 Rev. 12/2023 version.

What changed or needs a fresh check

  • Edition date: Verify you have the 2024 Rev. 12/2023 edition.
  • Fee: No filing fee for Form 3921.
  • Mailing address: Use the IRS address in the instructions for paper filing.
  • Electronic filing: Use the FIRE system if filing >250 forms.
  • Signature: No signature required on the electronic version; paper version must be signed by an authorized officer.

Form Preview

Form 3921 page 1

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Form 3921 page 2

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Quick Facts

The employer (or the plan administrator) files Form 3921.
It captures the employee’s name, SSN, date of exercise, number of shares transferred, exercise price, and fair market value on the exercise date.
The form is due to the IRS by February 28 (or March 31 if filed electronically) of the year following the exercise, and a copy must be given to the employee by January 31.
File electronically through the IRS FIRE system or mail paper copies to the IRS address listed in the instructions. Provide the employee copy by mail or secure electronic delivery.
Incorrect data can trigger penalties, cause mismatches with the employee’s tax return, and lead to IRS notices for both parties.
Gather the ISO exercise records for the calendar year. Fill each line with the employee’s identifying info and the transaction details. Run a totals check, then submit the batch electronically or by mail. Finally, send the employee copy and retain a copy for your records.

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After you file

  1. 1Store the filed form and supporting documents in a secure, searchable archive.
  2. 2Record the IRS acknowledgment number or certified mail receipt.
  3. 3Reconcile the filed data with the employee’s year‑end W‑2.
  4. 4Monitor for IRS notices and be ready to amend if errors are found.
  5. 5Update the equity plan system to mark the exercise as reported.
  6. 6Prepare for next year’s filing by confirming the current edition.

Sources

  • SRCIRS Form 3921 instructionsofficial PDF
  • SRCIRS Publication 525Taxable and Nontaxable Income (ISO section)
  • SRCIRS FIRE system guidelineselectronic filing requirements
  • SRCIRS deadline calendarFeb 28 paper, Mar 31 electronic
  • SRCForm 3921 revision history2024 Rev. 12/2023
  • SRCIRS penalty schedule for late or incorrect filings

Common confusion points

ISO vs. NSO

Employees often think any stock option uses Form 3921

→ Verify option type first

Exercise price vs. FMV

Columns are easy to swap

→ Double‑check against grant paperwork

Electronic vs. paper deadline

Different cut‑off dates

→ Use the later March 31 date for FIRE

Employee copy deadline

Some think it’s the same as IRS deadline

→ Must be sent by Jan 31

TCC requirement

Needed only for electronic batches >250

→ Confirm TCC status before uploading

Workflow map

Related forms and next steps

4 signals

Before

Form 4095 – Report of Section 83(b) election (if applicable)

Current

3921

After

Form 8949 – Report any disqualifying disposition of ISO shares

Often used with

Form W‑2 – Include ISO exercise info in Box 12 code V

⚠ If something goes wrong

  • Form 1099‑MISC – May be issued for corrective reporting

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Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
Public DomainCreated by the U.S. federal government. Not subject to copyright (17 USC § 105). Freely copyable without restriction.
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