The income tax filing lines at the post office may be shorter than last year's by more than two million taxpayers.
The Treasury Department says as of last week, more than 2.4 million people had taken advantage of free software to file their returns electronically.
The IRS Web site gives taxpayers the computer tools they need to file over the Internet.
Some consumer groups have complained about the program because users also get solicitations and advertisements from financial services companies.
The IRS had set a goal of two million electronic filers this year. It exceeded that even before the last-minute crush of taxpayers.
The government also says electronic filers will get their refunds faster.