DALLAS -The IRS expects to receive as many as 10 million tax returns from taxpayers who used Form 4868 to request a six-month extension to file their returns. Although most filers will need to get their return in by the Oct. 15 deadline, some taxpayers can wait until after Oct. 15 to file, including those serving in Iraq, Afghanistan or other combat zone localities and people affected by recent natural disasters.

"The extension deadline is usually the last day to take advantage of IRS e-file or the Free File program for the tax year," said Clay Sanford, an IRS spokesman in Dallas. "E-file is the fastest, easiest way to file your taxes, plus, it does the math for you, so there's less chance of making a mistake."

The Free File program provides free federal income tax preparation and electronic filing for eligible taxpayers through a partnership between the IRS and the Free File Alliance LLC, a group of private sector tax software companies. See IRS.gov for more details.