Learned this the hard way. Had a Delaware LLC I formed in 2020 for a side project that never took off. Forgot about it completely until I got a letter from the Delaware Division of Corporations saying I owed $900+ in back taxes and penalties. And I had ZERO revenue.
Ended up having to hire a registered agent to handle the dissolution paperwork since I didn't have a Delaware address. Total cost to clean up a company that never did anything: about $1,400. Expensive lesson in why you should dissolve entities you're not using.