When something is "due," it means it is required or expected to happen or be done at a certain time. There are plenty of synonyms for "are due" that can be used in various contexts. "Scheduled" is a good option when referring to something that has a set time or date. "Expected" can be used when the timing is uncertain but anticipated. "Owed" is a synonym that works when discussing payment or debts while "imminent" can be used when something is about to happen. "Pending" is also a good choice when discussing something that is awaiting completion. Ultimately, choosing the right synonym will depend on the context of the sentence in which it is used.