Already knew that Liberland existed although I never took it serious because come on, it can't function as a country, but I didn't think of it as a tax haven yet.
I still don't think it's going to work out exactly, it simply won't be recognised since the land is still Serbian by my logic and probably by theirs as well.

The fact is that Serbia claims the borders should be different from how they currently are, meaning Serbia gets a nice extra chunk of land while 2.7 square miles would go to Croatia according to Serbia. Since Croatia doesn't agree to this division, this new division isn't happening.

To say the land belongs to no one simply because the owner (Serbia) claims it should belong to someone else (Croatia) seems like a very flawed logic.

Calling it a sovereign nation was a funny joke I hadn't heard before either.

I'd say that if it does become a tax haven somehow, Serbia and Croatia will do something about it soon enough. It just looks like someone is hoping to abuse a misunderstanding to create a tax haven and I doubt it works because it has so little legitimacy.