Center on Budget and Policy Priorities (CBPP):
“Egregious employment tax noncompliance” by employers has risen substantially in recent years while the IRS’s ability to recover the lost revenues and investigate fraud and embezzlement has fallen, a report by the Treasury Inspector General for Tax Administration (TIGTA) finds. More than 1 million employers owed over $45 billion in unpaid employment taxes as of December 2015, including interest and penalties. The report provides further evidence that the deep cuts to IRS funding since 2010 have weakened the agency’s ability to perform its core functions of collecting taxes and enforcing the nation’s tax laws.
This type of employer tax evasion is particularly harmful; it not only reduces federal revenues but it also hurts workers because employers often don’t report their earnings to the IRS and Social Security Administration. That makes it hard for employees and their families to claim the benefits they’ve earned when they retire, become disabled, or die and leave dependents behind. ...The "employment tax" they're talking about is F.I.C.A., the tax that goes to the Social Security trust funds.