If you need some extra time to file your taxes, the first question to ask is why. If it’s because you don’t have the money to pay in time, this is not the kind of case where you will be granted an automatic extension. Instead, you will have to file an Internal Revenue Service (IRS) Form 1127, which is a request to extend the deadline to pay your taxes generally for up to 6 months. You’ll need to accompany the form with thorough documentation of your assets and income. The IRS will scrutinize this very closely, and you’ll need to convince them that you not only lack the disposable income to pay them on time, but also that you have no realistic way of borrowing the money.
If instead the problem isn’t that you lack the money to pay, but that you just aren’t going to be able to file on time (perhaps due to a delay in getting certain documents you need, say), then that’s a different case. The IRS provides a procedure for an automatic six month extension of the filing deadline to October 15.
To request this extension, simply file IRS Form 4868 and submit it by the April 15 deadline that your taxes would normally be due.
If you’re going to claim the automatic extension, you’ll want to first estimate your taxes as best you can, and enclose that amount of payment, or a little more to be on the safe side, when you submit Form 4868. Because, again, the automatic extension protects you from penalties for filing late, but it does not protect you from penalties for paying late.
Avoiding the penalties for filing late is not a trivial matter, so getting an extension can definitely be worthwhile. The penalty for filing late is 5% of the tax owed for every month or partial month you are late filing, up to five months.