The IRS doesn't like to talk about it, but penalties for filing late federal tax returns apply only to people who owe money. The penalty is a percentage of what you owe. If you owe nothing, there is no penalty.
But it doesn't make much sense to file late if you are owed a refund. And beware - if you have unpaid taxes, the late fees add up quickly.
The failure-to-file penalty is generally 5 percent of your unpaid tax bill for every month, or part of a month, you are late. It kicks in on April 19. In general, the maximum penalty is 25 percent of your original tax bill.
There also is a penalty for failing to pay your tax bill, separate from the penalty for failing to file at all, but it's much smaller. That's because the IRS wants you to file a return even if you don't have enough money to pay your bill.
The failure-to-pay penalty is 0.5 percent of your unpaid taxes for every month, or part of a month, you don't pay.