"If you don't own the private keys to the wallet containing Bitcoins, you don't own Bitcoins."
Put your BTC in brain wallet. Tell IRS "I don't have the private keys to that address".
Impossible for them to legally prove you are the owner of those BTC.
You pay no taxes.
You pay no taxes as long as you don't use it to buy something, which is the same as not having any BTC.