Puerto Rico recently passed what are known as Act 22 and Act 20, or the Individual Investors Act and Export Services Act. They allow new residents of Puerto Rico to be completely exempted from Puerto Rican taxation on their capital gain, dividend and interest income. And the Export Services Act levies a top 4% tax rate on earnings from businesses that perform services, like professional consulting, asset management, research and development, computer programming, and so forth, in Puerto Rico for clients outside of Puerto Rico
No need to move to Malta,
http://etfdailynews.com/2014/04/09/puerto-ricos-tax-benefits-more-than-the-better-florida/
Thanks in advance CPAs 
Puerto Rico recently passed what are known as Act 22 and Act 20, or the Individual Investors Act and Export Services Act. They allow new residents of Puerto Rico to be completely exempted from Puerto Rican taxation on their capital gain, dividend and interest income. And the Export Services Act levies a top 4% tax rate on earnings from businesses that perform services, like professional consulting, asset management, research and development, computer programming, and so forth, in Puerto Rico for clients outside of Puerto Rico.
I'm working on a blog about Puerto Rico tax incentives for American investors, traders and investment managers.
The big tax benefit is on capital gains which are sourced where the seller's tax home is. But some local tax advisors question whether Hacienda will allow act 22 exclusion on very active trading since they may argue it's not passive income.
I'm trying to get a definitive answer on that Important question. I'll publish the blog afterwards.