Since July 9, naturalized citizens of Taiwan have been permitted to have a romanized form of their original name included along with their adopted “Chinese name” on their household-registration certificate (hùkǒu). (This is an important government document that states your official residence.)
For example, my original name is Mark Swofford. My Mandarin name is Shǐ Wěifán (史偉凡). If I were to take ROC citizenship (which I’d like but am unlikely to try to gain until Taiwan drops its insistence that I first renounce my U.S. citizenship), my household-registration certificate would have “史偉凡” and could now also have some romanization. But … the romanization would have to be along the lines of Make Siwafo’erde.
What I could not have, according to the new regulations, would be either my original name or a romanization of my Mandarin name (i.e., neither “Mark Swofford” nor “Shi Weifan” would be permitted). Instead, I’d have to use a romanization of a Sinicized form of my original name (Make Siwafo’erde).
This is, well, rather odd. But I called the Ministry of the Interior and received confirmation. Apparently it’s part of the Legislative Yuan’s idea of helping Taiwan’s internationalization. I suppose this is a half step forward. Before the change, the only thing allowed would have been a name in Chinese characters and only Chinese characters.
source: Ministry changes name regulations for naturalization, Taipei Times, July 9, 2009