> intellectual property

this type of property is notoriously easy to hide!

Taxing income is the least worst. The best is taxing capital gains/profits from corporations.

> this type of property is notoriously easy to hide!

Not if you want it to be protected by a patent, trademark, or copyright.

IP offshoring is a big tax avoidance strategy already. Not that it couldn't be made harder to exploit, but it's not a fait accompli to simply tax the IP resident in a country.

You tax it at the point of enforcement. If someone wants to avoid paying the tax, then everybody gets to copy their stuff for free. It seems straightforward to me.

Sure, because we don't have an asset tax. If we had an asset tax, you'd have to register your IP. If you don't register your IP, you don't get protection. Not too different from real estate; if you don't have title, you don't own it.

I haven't considered all the economic consequences of this, but it does seem like enforcement is a minor problem.

Taxing IP would be counterproductive, except as a pure revelation mechanism for "IP that its owners actually care about". The whole point of IP is to be an incentive for creative work, and taxes destroy that incentive. It's better to roll IP rights back, and/or have rigorous requirements (such as registration and archiving of the work which is to be protected), but have very limited taxation on the IP itself.