From http://seattletimes.nwsource.com/html/nationworld/2017113852_immigtaxes29.html In 2009, the last year for which figures are available, employers reported wages of $72.8 billion for 7.7 million workers who could not be matched to legal Social Security numbers. That total hit a record $90.4 billion, earned by 10.8 million workers, in 2007, just before the recession. Some of those were legal workers who simply made paperwork mistakes, but the majority are believed to be illegal immigrants. Because those wages were reported by employers and not paid under the table, Social Security and Medicare deductions had to be made. A total of 12.4 percent of those wages went into the SSA system — 6.2 percent paid each by the worker and the employer. An additional 2.9 percent was paid into Medicare, half by the worker and half by the employer. That means about $11.2 billion went into the Social Security Trust Fund in 2007, and $2.6 billion went into Medicare. While that money will be used to pay retirees and health-care beneficiaries, it most likely will never be claimed by the illegal immigrants who contributed it.