The IRS announced that it has shut down the electronic filing PIN tool as a precautionary measure against a recent rise in cyber attacks. 

Hackers broke into the IRS's e-File PIN system in February and accessed more than 100,000 PINs through the tool, using personal information they'd obtained from other sources. The IRS did not shut down the program at the time because it is used in almost all commercial software products. However, the IRS decided to shutter the program now after detecting additional automated attacks taking place at an increasing frequency. 

The IRS said that the change only affects a small portion of taxpayers who did not file their returns this year and needed a replacement PIN. It also pointed out that it has already been planning to end the program due to security concerns, and has been working with tax software providers to make the transition as smooth as possible.