The government, at times

TAXER

It collects what’s due but isn’t a person or a bill collector.

This clue plays on the idea that governments collect taxes, so "the government" can be thought of as something that taxes—or a "taxer." The word "at times" hints that it’s not always the case, but it’s a common role. It’s a straightforward definition with a slight twist, turning a noun (government) into an agent noun (taxer) to fit the answer.