“This time, the IRS detected ‘automated attacks taking place at an increasing frequency’ thanks to the additional defenses it added after that initial hack. It said only ‘a small number’ of taxpayers were affected, but it didn’t give an exact number. The IRS chose not to kill the tool back in February, since most commercial tax software products use it. After these recent cyberattacks, though, the agency determined that it would be safer to give up on a verification method that’s scheduled for the chopping block anyway.”
Source: IRS kills e-filing PINs prematurely due to cyberattacks