Proficiency Bonus

Characters have a proficiency bonus determined by level, as detailed in chapter 1. Monsters also have this bonus, which is incorporated in their stat blocks. The bonus is used in the rules on ability checks, saving throws, and attack rolls. Your proficiency bonus can’t be added to a single die roll or other number more than once. For example, if two different rules say you can add your proficiency bonus to a Wisdom saving throw, you nevertheless add the bonus only once when you make the save. Occasionally, your proficiency bonus might be multiplied or divided (doubled or halved, for example)