Though the Commonwealth government has its own tax laws, Puerto Ricans are also required to pay most U.S. federal taxes, with the major exception being that some
residents do not have to pay the federal personal income tax. In 2009, Puerto Rico paid $3.742 billion into the US Treasury. Residents of Puerto Rico pay into Social Security, and are thus eligible for Social Security benefits upon retirement. However, they are excluded from the Supplemental Security Income (SSI), and the island actually receives a small fraction of the Medicaid funding it would receive if it were a U.S. state. Also, Medicare providers receive less-than-full state-like reimbursements for services.
Bona fide residents of Puerto Rico cannot
claim deductions and/or credits allocable to or chargeable against Puerto Rican source income that is excluded from a U.S. tax return. http://en.wikipedia.org/wiki/Taxation_in_Puerto_Rico