Get Answers Support Tax Filings & Payments Other Forms Form 3921 When is the deadline for Form 3921? Last modified 9/26/2023 1:18:02 AM EST When filing Form 3921, you must adhere to the following deadlines: January 31 is the deadline for all employees who used ISOs the previous year to receive copy B. The IRS must receive copy A by February 28 if you are filing on paper. The IRS must receive copy A by March 31 if you are filing electronically. An IRS filing deadline is automatically extended to the next business day if it falls on a holiday or the weekend. Click here to file Form 3921 for 2022. Was this helpful? Yes No Need more help? Get in touch with our dedicated support team Contact Us (704) 684-4751 support@taxbandits.com Sign Up for a FREE TaxBandits Account! The Smart CPA Choice Register Now Already have an account? Sign in