Some IRS computer systems resume operation

Some IRS computer applications resumed operation Thursday, a day after a suspected hardware failure knocked them out of service, the nation's tax agency said.

The "Where's My Refund" feature ^[1] on the IRS.gov website that enables taxpayers to check on the status of their payment checks and other programs came back online, but the IRS tax-return processing system remained down as of Thursday afternoon, the agency said in a brief statement.

"We hope to have that back up again running at some point today," the IRS said of the system used to process tax returns for millions of Americans.

Although the electronic e-filing system for individual taxpayers and businesses remained unavailable, the IRS said taxpayers may continue their normal annual process of sending the returns to their e-file providers, such as tax preparation firms. The companies will hold the tax returns until the IRS resumes regular operations, the agency said.

Despite the electronic outage, the IRS continued to predict that nine out of 10 taxpayers would have their tax refunds issued within 21 days.

"The IRS is continuing to examine the underlying cause of the outage yesterday," the agency said. "It's important to note that at this time this situation appears to be a hardware failure."

Although the agency also said there was no evidence of any external involvement in the outage, at least one IRS critic suggested the computer systems may have been attacked by electronic hackers.

"My initial gut reaction is that it may be a hack," Rep. Jason Chaffetz, R-Utah, the chairman of the House Committee on Oversight and Government Reform, said in a Fox Business interview ^[2]. "You just don't have systems collapse and people can't use the systems online. It's not like they run out of batteries or something."

The tax agency offered no immediate response to Chaffetz, who last year called for the impeachment of IRS Commissioner John Koskinen ^[3] for failing to comply with congressional subpoenas and preserve documents.

The IRS has suffered numerous previous computer-related problems, ranging from failures in database controls to failing to screen workers who had access to personal data for millions of taxpayers.

Cyber-thieves in 2015 stole as much as $39 million by filing approximately 13,000 fraudulent tax refunds after gaining access to taxpayer information, Koskinen told Congress in June.

The IRS indicated in August that the attackers succeeded in obtaining access to information from more than 350,000 taxpayer accounts, according to an October management report by J. Russell George, the federal inspector general who oversees the tax agency.

Follow USA TODAY's Kevin McCoy at @kmccoynyc.