To prepare your tax return, you’ll need a form W-2, or Wage and Tax statement, from each organization your worked for during the previous year. And even though tax-filing season starts on Jan. 19 this year, your employer has until the end of January to mail out your W-2. If you don’t receive the form by mid-February, contact your employer to inquire if and when it was mailed. It is possible your employer has an old or incorrect address listed for you, or that your employer sent the form electronically to your email inbox. Request that the W-2 be resent if you don’t unearth it in your email, and ask when you can expect to receive it. Contact the IRS if your employer is not being cooperative. Call 800-829-1040 and be prepared to provide the following: Your name, address, Social Security number, phone number Employer’s name, address, and phone number Dates of employment An estimate of the wages you earned and the federal income tax withheld (You can use your final pay stub of 2015 to figure this out.) Even if you do not receive your W-2 form before the tax filing season ends, you still must file your taxes or request a six-month extension by the tax-filing deadline (which is April 18 in 2016 thanks to Emancipation Day celebrations in D.C. happening on the traditional deadline of April 15). If you’ve contacted both your employer and the IRS and are not filing for an extension, fill out Form 4852, the substitute for the W-2. Attach the form to your return, estimating income and withholding taxes as accurately as possible. There will likely be a delay in processing your refund, if you’re due one, as the agency will need to verify your estimates. Read Next: You Can File Your Taxes Next Week—and Being an Early Bird is Smart If you receive your missing W-2 after you’ve filed your return using Form 4852, and the information is different from what you reported, you will have to amend your return by filing Form 1040X.