The Treasury Inspector General for Tax Administration (TIGTA) issued a report Tuesday which found the IRS had identified 1.1 million cases of employment-related identity theft since 2011 but failed to notify the victims. As the IG’s press release makes clear, TIGTA pointed out this same problem to the IRS in a previous audit:

In July 2011, TIGTA reported that the IRS was in a unique position to identify cases of employment-related identity theft. TIGTA recommended that the IRS implement procedures to timely alert taxpayers when it becomes aware that their identity was stolen. However, in this review, TIGTA determined that taxpayers are still not notified.

During the period February 2011 to December 2015, the IRS identified almost 1.1 million taxpayers who were victims of employment-related identity theft.

Employment related identity theft involves the use of someone else’s Social Security Number to get a job. The IG’s press release explains, “Taxpayers may first realize they are victims of this type of crime when they receive an IRS notice of a discrepancy in the income they reported on their tax return.”

Why is the IRS so hesitant to deal with this problem? Because most of the people committing the identity theft are illegal immigrants. From the Hill:

The issue has gotten attention in Congress, in part because illegal immigrants tend to be those using other people’s Social Security numbers to get jobs and file their taxes with ITINs. During hearings in April, IRS Commissioner John Koskinen said that the IRS doesn’t go after illegal immigrants who do this because the agency wants them to pay the taxes they owe. Koskinen’s comments have drawn criticism from Republican lawmakers.

The IG report does not explicitly mention illegal immigrants and does not discuss whether the IRS should be alerting immigration authorities about illegal immigrants who use other people’s Social Security numbers to get jobs. Instead, it focuses on the agency’s failure to notify people whose numbers were used by others.

It’s not hard to guess why the IRS is not informing taxpayers that their SSN has been used by an illegal immigrant. If they did, that would upset a lot of people and could lead to a push for the IRS to actually do something about the thieves, i.e. report them to ICE. But the IRS doesn’t want to be involved in enforcing immigration laws. The official explanation is that doing so would discourage people (again, illegal immigrant identity thieves) from paying taxes. The Hill reported in April:

[IRS Commissioner] Koskinen defended the agency’s approach when speaking to reporters after Wednesday’s hearing in the House.

“If people with ITINs think the fact that they file with us means they’re now in jeopardy, a lot of them are going to quit filing with us,” he said.

He added, “What we can’t afford to do is have people feel, ‘If I pay my taxes to the IRS, they’re going to quickly check with immigration, they’re going to check with social security, they’re going to check with everybody,’ and even if they are here legitimately, a lot of times they’re uneasy about dealing with authority.”

So there you have it. The IRS has known this was a problem since 2011. Since then it has identified an additional 1.1 million victims of employment related identity theft and, with the exception of a 2014 pilot program, failed to notify the victims. The IRS’ stated reason for not doing more to stop this is that it doesn’t want to discourage the illegal immigrants who use identity theft to get a job from filing tax returns.