The IRS has failed to police the huge tax breaks offered by Puerto Rico, whistleblower claims

• The IRS's probe into the abuse of a Puerto Rican tax benefit has made little progress, a whistleblower said.
• In a letter reviewed by The New York Times, the insider says that less than 1% of beneficiaries were audited.
• The tax break allows new residents of Puerto Rico to be exempt from local taxes on investment profits.

A whistleblower claims that the Internal Revenue Service has not done enough to stop the exploitation of a Puerto Rico tax break, The New York Times reported.