Have you done your taxes yet?

If not, you’re far from alone. In 2015, according to data from the IRS, more than 20 million Americans — about one in seven filers — waited until the final week to file their federal income tax returns, which this year are due on April 18. (Quirks of the calendar pushed tax season three days past its usual April 15 end date.)

This year, the number of procrastinators could be even higher. Tax season got off to a slow start in 2017, perhaps because people hoped President Trump’s promised overhaul of the tax code could save them money. (Realistically, any changes to the tax code wouldn’t have taken effect in time for this year’s filings — and in any case, the overhaul is moving slowly.)

Can’t get your paperwork together in time? The IRS grants an automatic six-month extension on filing (but not paying) your taxes. But for most people, it’s best to file as soon as possible for one simple reason: Three-quarters of households get a refund.