While many Americans believe that illegal immigrants don't pay taxes, the Social Security Administration sees billions of dollars flow into its coffers every year that have been deducted from paychecks issued to undocumented workers using false names and phony Social Security numbers - money those workers will almost certainly never see again.

SSA officials keep a record of total wages that do not match up with real names and numbers in their system. The record is called the earnings suspense file.

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.

In 2007, just before the recession, that total reached a record of $90.4 billion earned by 10.8 million workers. Some of those were legal workers who simply made mistakes in their paperwork, but it is believed that the majority were undocumented.

Since 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, most of it likely will never be claimed by the undocumented workers who contributed it.

Since the passage of 2010's payroll tax cut - which Congress on Friday extended through February - workers have paid 4.2 percent to Social Security instead of 6.2 percent.

"When you hear people voicing anti-immigrant sentiments, one of the first things they say is, 'They don't pay any taxes, and they just take money out of the system,' " said Jeannie Economos of the Farmworker Association Florida, based in Apopka. "But that just isn't true. Yes, some are paid under the table, but the majority are paid by check, and they pay taxes out of those checks."

Fake SS cards prevalent

For many employers, the move away from paying undocumented workers under the table came in 1986. That was the year President Ronald Reagan signed an amnesty that made about 2.8 million undocumented workers legal. But part of that law - the Immigration Reform and Control Act - requires that employers demand proof that a worker has a legal right to work in the United States.

Employers are obligated to ask for a Social Security number, but they don't have to confirm that it is real. That has led, over the years, to the printing of millions of false Social Security cards that are sold to newly arrived undocumented workers.

The SSA notifies employers every year of Social Security numbers and workers that don't match up. Employers tell employees they have to get new cards.

"And they simply do it all over again the next year with a new number," said attorney Greg Schell of the Migrant Farmworker Justice Project in Lake Worth.

A false SSA card, accompanied by a phony alien registration card - known as a green card - can be had for about $200 in Florida, Economos said.

Some immigrant advocates encourage undocumented workers to save all their check stubs in the hope that if another amnesty is approved they might be able to claim their Social Security benefits someday, but Schell sees that as very unlikely.

"Many of these workers have used lots of different names and numbers so that it would be quite a project to go back," he said. "They almost certainly will never get back the money they are paying, and so they are helping keep Social Security solvent."

Ira Mehlman, spokes man for the Federation for American Immigration Reform, a leading voice for stricter immigration enforcement and against amnesty, concedes that illegal immigrants put billions of dollars into Social Security. He says the figure he has heard is about $7 billion per year in total FICA contributions - Social Security plus Medicare.

"But that $7 billion figure pales when compared to the cost of having illegal aliens here," Mehlman said.

His federation estimates that local, state and federal spending on illegal immigrants - mainly for education and health care - costs about $100 billion per year.

Just happy to have a job