Puerto Rico has a unique relationship with the U.S. when it comes to taxes. A Puerto Rico corporation can do business with a U.S. corp and not pay any U.S. taxes. The employees of the PR corp that are residents in PR only pay PR taxes not IRS taxes.

I posted my email address to another comment here. If you are interested send me an email and I will put you in contact with a tax accountant here and a few others that work on this.