Updated

The IRS stopped accepting electronically filed tax returns Wednesday because of problems with some of its computer systems. The outage could affect refunds, but the agency said it doesn't anticipate "major disruptions."

A "hardware failure" forced the shutdown of several tax processing systems, including the e-file system, the IRS said in a statement. The IRS.gov website remains available, but "where's my refund" and other services are not working.

Some systems will be out of service at least until Thursday, the agency said. "The IRS is currently in the process of making repairs and working to restore normal operations as soon as possible," the IRS said.

Taxpayers can continue to send electronic returns to companies that serve as middlemen between taxpayers and the IRS. But those companies have to hold on to the tax returns until the IRS systems are up and running again, the IRS said.

While the IRS said it is still assessing the scope of the outage, it expects 90 percent of taxpayers will receive refunds within three weeks.

People who have already filed returns don't need to do anything more, the IRS said.