Update 10/13/17 - IRS has extended relief for this tax deadline to taxpayers affected by California wildfires in certain counties. IR-2017-167, Oct. 3, 2017 WASHINGTON – The Internal Revenue Service has an important reminder for taxpayers who filed for an extension and face an Oct. 16 filing deadline: The adjusted gross income (AGI) amount from their 2015 return may be needed to electronically file their 2016 tax return. For those taxpayers who have a valid extension and are in or affected by a federally declared disaster area may be allowed more time to file. Currently, taxpayers impacted by Hurricanes Harvey, Irma and Maria as well as people in parts of Michigan and West Virginia qualify for this relief. See the disaster relief page on IRS.gov for details. As a reminder, taxpayers should keep a copy of their tax returns and supporting documents for a minimum of three years. Prior year tax returns are even more important as the IRS makes changes to protect taxpayers and authenticate their identity. Extension filers should plan ahead if they are using a software product for the first time. They should have kept a copy of their 2015 tax return or if not, will need to order a tax transcript, a process that may take five to 10 calendar days. The AGI is clearly labeled on both the tax return and the transcript. Taxpayers who prepare their own electronic tax returns are required to electronically sign and validate their return. Using an electronic filing PIN is no longer an option. To authenticate their identities, taxpayers will also need to enter either of two items: their prior-year AGI or their prior-year self-select PIN and their date of birth. If married filing jointly, both taxpayers must authenticate their identities with this information. Generally, tax-preparation software automatically generates the prior-year AGI and/or self-select PIN for returning customers. However, taxpayers who are new to a software product must enter the prior-year AGI or prior-year self-select PIN themselves. How to Find AGI; Plan Ahead if a Mailed Transcript Needed The adjusted gross income is gross income minus certain adjustments. On 2015 tax returns, the AGI is found on line 37 of Form 1040; line 21 on Form 1040A and line 4 on Form 1040EZ. Taxpayers who e-filed and did not keep a copy of their original 2015 tax return may be able to return to their prior-year software provider or tax preparer to obtain a copy. Those who lack access to their prior-year tax returns also may go to irs.gov/transcript and use Get Transcript Online or Get Transcript by Mail. A transcript is a summary of the tax return or tax account. There are various types of transcripts, but the Tax Return Transcript works best. Look for the “Adjusted Gross Income” amount on the transcript. Taxpayers must pass Secure Access authentication in order to access Get Transcript Online and immediately access their transcripts. Those who cannot pass Secure Access authentication should use Get Transcript by Mail or call 800-908-9946, and a transcript will be delivered to their home address within five to 10 calendar days.