The article is in reference to (but doesn't mention) the "Individual Investors Act (Act 22)"[1], which exempts you from Puerto Rico's own income tax, and limits your IRS liabilities for capital gains tax on long term investments sold within the first ten years of your residency.
Regardless of if you take advantage of the above, you are exempt from Federal taxes.
The article is in reference to (but doesn't mention) the "Individual Investors Act (Act 22)"[1], which exempts you from Puerto Rico's own income tax, and limits your IRS liabilities for capital gains tax on long term investments sold within the first ten years of your residency.
Regardless of if you take advantage of the above, you are exempt from Federal taxes.
This is just an incentive atop it.
[1] http://businessinpuertorico.com/en/profit/individual-investo...