If you haven’t filed your tax return yet, time is getting short. But you aren’t alone in procrastinating.

The number of individual tax returns received by March 29 was down more than 1 percent from the same time last year, the Internal Revenue Service reported, and the size of the average refund declined by 0.7 percent, to $2,873.

The decline may be because taxpayers are still trying to understand the impact of the Tax Cuts and Jobs Act of 2017, which made sweeping changes in tax forms, brackets, rates and deductions.

“This is the most complicated tax season ever,” said Ross A. Riskin, a certified public accountant and an assistant professor of taxation with the American College of Financial Services.