April 18*, 2011 Due Date for Federal Income Tax Returns (and Tax Extension requests) - Tax Day for Tax Year 2010 - Filing Deadline
April 18, 2011 Due Date for State Income Tax Returns (for many states - check with your state tax agency) - Tax Day for Tax Year 2010 - Filing Deadline
April 18*, 2011 Due Date for Tax Extensions for Federal Income Tax Returns for Tax Year 2010.
From April 1, 2011 until April 15, 2011 you can prepare and efile a Federal Tax Extension on efile.com. Tax Return or Tax Extension?
April 18, 2011 Due Date for State Income Tax Extension requests (for many states - check with your state tax agency).
Find State Tax Return Extension Due Dates
October 17**, 2011 Last day to efile a 2010 Income Tax Return for tax extension and late tax efilers - Important notice
October 20, 2011 Last day to prepare and/or print a 2010 Tax Year Income Tax Return on efile.com -- no electronic submissions to IRS after October 20, 2011
Information from http://www.efile.com/tax-day-deadlines/