Senate Finance Committee Chairman Orrin Hatch attacked the IRS Tuesday after thieves hacked one of the agency's online services and stole the confidential tax information of more than 100,000 taxpayers.
"Taxpayers must know that the information they send to the IRS is secure," the Utah senator said. "And hackers who would steal that information must know that they will suffer severe consequences for their crimes."
The hackers breached the IRS' "Get Transcript" system — clearing a security screen that required knowledge about the taxpayer, including Social Security number, date of birth, tax filing status, and street address. The agency's primary computer system was not jeopardized.
The theft occurred from February to mid-May, IRS officials said Tuesday and the service has been temporarily shut down.
Hatch said Tuesday that IRS Commissioner John Koskinen told him of the theft in a telephone conversation last week. The finance committee immediately began its investigation.
"The committee has been working with the IRS to better understand the nature of the attack, what information was compromised, and how such a devastating breach could occur," Hatch said. "That the IRS, home to highly sensitive information on every single American and every single company doing business here, was vulnerable to this attack is simply unacceptable.
"What’s more, this agency has been repeatedly warned by top government watchdogs that its data-security systems are inadequate against the growing threat of international hackers and data thieves.
"The first order of business is for the federal government to determine who was behind the attack and take aggressive action against them. Secondly, we must determine what information was stolen and how it will affect taxpayers.
"Finally, the Congress and the administration must work together to better protect taxpayer information from cyberthreats," Hatch said.
The Associated Press contributed to this report.