Employers are required to send you a completed Form W-2 showing your compensation and tax withholding amounts for the year via mail before January 31st. If it’s past January 31st and you have not received your W-2 form you should contact your employer to make sure it was mailed to the correct address. If it’s past February 15th and you still have not received the form, you can call the IRS at 1-800-829-1040 to file a complaint.