WASHINGTON (AP) — Here's a little secret for all you procrastinators on Tax Day: The Internal Revenue Service doesn't like to talk about it, but as long as you don't owe any additional taxes, there is no penalty for filing a few days late.

The late filing penalty is usually 5 percent of the unpaid taxes for each month — or part of a month — a return is late. That can add up quickly if you owe additional taxes. But what if the unpaid taxes are zero? Five percent of zero is ... zero!

However, if you wait more than three years to file, you forfeit your refund. So maybe it's better to file by Monday, after all. Besides, if you're getting a refund, why wait?

The IRS got a late start on tax season this year, thanks to a last-minute tax law passed by Congress on Jan. 1. But the deadline for filing returns didn't change, so if you owe money, it's time to settle up with the government.

In all, the IRS expects to process 149 million returns from individuals this year, including returns from people who file for 6-month extensions. About a quarter of returns are usually filed in the last three weeks before Tax Day. This year the IRS received more than 10 million electronically filed returns from Friday through Sunday.