The term "flag-of-convenience" refers to certain countries such as Panama, Liberia and Singapore, who authorize foreign ships to register with their country and operate under their flag. Aside from a registration fee and tonnage tax, the foreign ships are free from any controls or obligations.
有些國家准許外國人所有的船舶，登記為該國國籍，懸掛該國國旗營運，僅收登記費，及每年按船隻噸位徵收噸稅，除此別無任何管制或要求。巴拿馬、賴比瑞亞和新加坡等國都施行此制度。