It’s April 15 — and you haven’t finished filing your taxes yet? That can make the annual accounting stressful, but it’s no surprise at the Internal Revenue Service.

Last year, 27.1 million people filed their taxes before the stroke of midnight, and the IRS said they expect one in five taxpayers to do the same thing again Tuesday.

And for those of you thinking, what to do?

“There is no need to be in line at the post office at midnight on April 15,” said Terry Lutes, the IRS director of electronic tax administration, in a press release. “Our best advice: e-file now; pay later. You can electronically file your returns and schedule a payment by April 15.”

And if you’re not done, more than likely it’s because you do owe money.

The IRS said 61 percent of balance-due returns arrive after April 15. Most of the returns filed before April 1 — nearly three-quarters of them — are for taxpayers expecting refunds.

If taxpayers really are not ready to file, they can submit a Form 4868 extension with the IRS. The form will extend the time to file the return to Oct. 15, but it doesn’t extend your time for payment. Interest and any penalties will add up, so the agency urges people to pay what they can now.

And if you and your envelope are just going to make it to a mailbox in time, here’s what you need to know about service hours from the United States Postal Service.

The closing time is the latest hour for a tax filing postmark at all offices except for the extended hours in South Bend. Call your local branch for more specific information.