According to the IRS, “People have until Tuesday, April 18, 2017 to file their 2016 returns and pay any taxes due. The deadline is later this year due to several factors. The usual April 15 deadline falls on Saturday this year, which would normally give taxpayers until at least the following Monday. However, Emancipation Day, a D.C. holiday, is observed on Monday, April 17, giving taxpayers nationwide an additional day to file.”
The filing date for Illinois State income tax returns is also April 18, 2017.