The antonyms for being in business could either be not being in business or being out of business. The former refers to a state of not having any venture or commercial engagement. That is, one is neither managing nor owning any enterprise or company. On the other hand, being out of business means that a business has ceased operations, either through bankruptcy or other reasons. While being in business conveys the idea of being operational and thriving, both of the antonyms present a situation where one is either not involved or has stopped being engaged in commerce.