What is the deadline due date "after" filing for an extension for a business?

Answer 1

For 2007, 1120S is delayed to 9/15, 1120 to 9/15 and 1065 to 10/15.

Sole proprietors file as part of their 1040, so delayed to 10/15.

Answer 2

  Normally, an extension gives you six months from the original due date for filing a return with no penalty for late filing.  Please remember that this extension time is for filing the return, not paying taxes due.  If you have a balance due, you may be liable for late payment penalties and interest.