you only have to pay tax on the eth you are staking when you unstake them and cash them out..

Also not a tax guy but that sounds optimistic. With mining generally you have to pay tax on the market value of the block reward you receive, even if you don't sell it. This is pretty typical for what happens when you earn something valuable that isn't your country's money; If they didn't make you pay tax on the actual value of the thing, people would create a massive barter economy where everybody paid each other in pogs or whatever and only cashed them out to regular money when they needed to.

With staking you can definitely make the argument that you haven't earned the revenue until you're actually *able* to cash it out, ie when withdrawals are enabled. But that's coming soon.