10. Missing the deadline
If the impending April 15 tax deadline is a problem for you, make sure you buy yourself six extra months by simply asking the IRS for more time to complete your tax paperwork. All you have to do is submit Form 4868, Application for Automatic Extension of Time to File US Individual Income Tax Return, by the regular filing deadline. Remember, though, that the extension is only for the forms; you still have to pay any tax you may owe by April 15.
If you make the mistake of not filing or paying on time, you'll end up facing even more costs in late-filing penalties and interest fees.