In an attempt to file fraudulent tax returns, identity thieves hacked IRS computer systems once again. In a statement from the IRS, they said they halted an attack attempting to access PIN information. An E-file PIN is used in some instances to electronically file tax returns.

The identity thieves stole social security numbers outside of the IRS, and, using that information, they attempted to create E-file PINs. No data was compromised or disclosed on the IRS computer systems.

They identified 464,000 unique social security numbers used in the unauthorized attempts, of which 101,000 were used to successfully access an E-file PIN. The IRS will notify affected taxpayers by mail that their SSN were used in the attempt and have marked their accounts to protect against any tax-related identity theft.

Last week the IRS had a systemwide computer failure and could not accept many tax returns. The IRS said in their statement that this incident is not related or connected to the outage last week.

In 2015 the IRS had a massive data breach that led to $50 million in bogus tax refunds. A later report found that the computer system the IRS used to detect identity theft may have been vulnerable to hackers.

For the full statement from the IRS, click here.