Read it and weep.
Taxation in Puerto Rico
Taxation in Puerto Rico takes the form of both Federal and Commonwealth taxes. Puerto Rico has independent tax-levying authority by provisions of 48 U.S.C. § 734 of the United States code.
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 most 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 rendered to beneficiaries in Puerto Rico, even though the latter paid fully into the system.
The federal taxes paid by Puerto Rico residents include import/export taxes, Federal commodity taxes, social security taxes, among others. Residents also pay Federal payroll taxes, such as Social Security and Medicare taxes.[1