When is the deadline to e-file a tax extension?
The deadline to e-file a tax extension form is the same as the original IRS deadline for the income tax form that you're requesting the extension. For example, if you're applying for an extension of time to file IRS Form 1120 - the original due date is March 15; therefore, your extension form would be due by March 15 as well. For personal tax extensions, the due date is typically April 17 which also means your extension form is due by this date as well.