Millions of Americans will participate in an annual rite this week: filing their taxes just before the deadline. Tax Day is April 15, meaning taxpayers must submit their returns or request extensions by Monday. As of March 29, 90 million households had already filed their returns. Based on historic trends, the IRS can expect about 20 million more to file in the final days.

WHEN IS THE LAST DAY TO FILE TAXES?

This year’s deadline falls on Monday, April 15, for most Americans, except for residents of Maine and Massachusetts, who have until April 17 because of state holidays. Taxpayers who have been affected by certain specific natural disasters also get an automatic extension; if you think this might be you, you can check the irs.gov site under “Tax relief in disaster situations.”

WHEN SHOULD I EXPECT MY REFUND?

If you filed your return online and you gave the IRS your bank account information for a direct deposit, you should see your refund within three weeks of filing. If you filed on paper or if you’re waiting for a check in the mail instead of a direct deposit, it might take longer. You can look up the status of your refund at irs.gov/wheres-my-refund.

WHEN ARE TAXES I OWE DUE?

Payments are due on the day that your tax return is due. If you can’t afford to cover all of what you owe, it’s still a good idea to pay at least some amount before the deadline to avoid owing late fees on the portion you paid. If you pay some portion and set up a payment plan (check irs.gov under “Pay”) with the IRS to pay off the rest, you can reduce the extra fees and interest due.

HOW DO I FILE FOR FREE?

There are many ways to file for free. Tax prep companies offer free software through the Free File program for anyone with an annual income of up to $79,000. That’s not to be confused with the IRS’s new Direct File tool, which allows qualifying taxpayers in 12 states to file for free if they have straightforward tax situations. And anybody can file for free, either online or on paper, by filling out the tax forms themselves.

WHAT IF I NEED HELP?

The IRS has been on a hiring spree that has let it open more in-person taxpayer assistance centers across the country and boast of better response rates when taxpayers call for help (check irs.gov/help). If you have a question, you’re probably more likely to get an answer now from the IRS than you were in recent years.

WHAT’S THE PENALTY FOR FILING LATE?

Yes. If you don’t pay on time, the IRS can charge you a fee for filing late and interest on what you owe. The amount will depend on how much money you owe and how long you wait to pay it. It’s better to formally request an extension than to simply let the deadline go by. To ask for an extension, you can either use tax software (including Free File) or mail a request to the IRS.

WILL THE POST OFFICE BE OPEN LATE ON TAX DAY?

Some post offices do stay open past their regular hours on the day of the tax deadline to allow people to make sure that their returns are postmarked April 15. The IRS counts the return as on-time as long as the postmark is on or before the deadline. Because the vast majority of Americans e-file their returns rather than mail them in, though, you shouldn’t expect a line at the post office