“There’s an old story about the Rolling Stones being tax exiled in France,” billionaire Phil Shawe, 55, says by video call from a white-walled office in Puerto Rico, the tropical sun peeking through the shutters. “I am tax exiled in Puerto Rico.” Shawe affectionately calls Puerto Rico the “one legitimate tax haven” in the U.S. He relocated to the island in 2018—the same year he won total control of his translation and language services firm TransPerfect—to counteract the effects of taxes related to the deal. Now, his primary residence is a sprawling Old San Juan mansion that was formerly home to the French consulate. The move was also a symbolic end to an intense battle between Shawe and his former fiancée, cofounder and business partner of more than 25 years, Liz Elting. The pair had founded #TransPerfect in a New York University dorm room in 1992 and continued to own and run it successfully for nearly two decades, even after she married someone else. Around 2011, though, things tur...