U.S. citizens who have lived all year on the island are exempt from filing taxes to the federal government of the United States as long as all of your income was from Puerto Rican sources only. However, if you receive income from anywhere else in the world, including the United States and/or if you are an employee of any agency of the United States in Puerto Rico, you must submit a form to the federal government.
So you shouldn’t file a tax return for the U.S. if you meet either of the following requirements:
you’re a bona fide resident of Puerto Rico during the entire tax year, and
Your only income is from sources within Puerto Rico.