Illegal immigrants cashing in on federal tax credits, study shows. Large numbers of illegal immigrants file tax returns using phony Social Security numbers to cash in on the federal Earned Income Tax Credit, thanks to lax government management, according to the author of a new study. “Technically, only people authorized to work in the U.S. are eligible for the credit, you need a valid Social security number,” said Ed Rubenstein, a financial analyst and economist, speaking at a news conference Tuesday at the National Press Club. “But identity theft, stolen Social Security numbers, and other scams effectively nullify...