What are the penalties and interest for filing taxes late?

It's April 19, and most Americans — except for residents of Maine and Massachusetts — should have filed their tax returns by yesterday.

Of course, life isn't that simple. Every year, about 20 million individual tax returns arrive in between the official end of tax season and the end of the year. Some tax payers will have filed an extension, while others may have simply delayed the pain of paperwork only to be surprised with a sizable financial penalty at the end.

When you owe taxes, delaying the dreaded task of filing can mean hundreds of dollars in extra penalties.