Can users add categories on their own?

I have not set up a classifieds site yet, on a network, but have question about categories and sub-categories.

Can a paid user add categories and sub-categories if one they need isn't already set up?

This would be helpful in getting started, since you can't bulk import a list of them, and for a general classifieds site, there could be LOTS of them. To be able to allow the users to add as needed would be helpful. Also the ability to bulk import them too.

I have plans on many classifieds sites, and don't relish the thought of recreating them over and over from scratch.