5 Tax Tips You Should Know Before the Filing Deadline

— -- If you haven't filed your taxes yet, you're not alone: 20 to 25 percent of all Americans wait until the last two weeks to file their taxes, according to the IRS.

Here are five frequently asked questions that can help you before the deadline, which this year is on Monday, April 18.

1. What if I can't make the deadline?

If you're not ready to file by April 18 (or April 19 for taxpayers in Maine or Massachusetts), you can fill out Form 4868 at IRS.gov, which provides an automatic six-month extension. But you still need to pay as much of what you think you owe in taxes, to reduce penalties and interest charges.

If you file a return but don't pay all the tax that's due, you will generally have to pay a late payment penalty. That's one-half of one percent for each month, or part of a month, up to a maximum of 25 percent of the unpaid amount, according to the IRS.

2. Where's my refund?

It can take about 21 days or less to get your refund, according to the IRS. You can start checking the status of your return at IRS.gov.

3. How much should I be getting back?

The IRS says that most people get something back. The average refund is about $3,000.

4. What happens if I don't file?

It depends. If you're owed money, you could lose your refund if you don't file your taxes within three years. If you owe the government, then you face interest charges, penalties or even criminal prosecution if you're a chronic non-filer.

Interest accrues on any unpaid tax from the due date of the return until the date of payment in full, according to the IRS, which determines the interest rate quarterly. It's the federal short-term rate plus 3 percent and the interest compounds daily.

If you owe tax and don't file on time, the penalty is usually five percent of the tax owed for each month, or part of a month that your return is late, up to a maximum of 25 percent, according to the IRS.

5. Will I get audited?

IRS audits are at their lowest levels in more than a decade and that trend may continue this year, IRS Commissioner John Koskinen said in a speech to the National Press Club last month. The vast majority of those who get audited are making a million dollars or more each year.