If a multiclass character's classes are not nearly the same level, then he suffers a multiclass penalty of -20% XP for each class that is not within 1 level of his most experienced class. These penalties apply from the moment the character adds a class or raises a class's level too high. For instance, a 4th-level wizard/3rd-level rogue gets no penalty, but if that character raises his wizard level to 5th, then he'd receive the -20% penalty from that point on until his levels were nearly even again. The penalty is -40% if three classes are uneven -- for instance, a 5th-level wizard/3rd-level rogue/1st-level fighter -- and -60% if four classes are uneven (a 7th-level warlock/5th-level wizard/3rd-level rogue/1st-level fighter).