I don´t think any government want tax from you if you only holding Bitcoin.  They want tax of the gains that you earn when you sell or trade with it.
In germany you only must pay tax if you hold the coin not longer as a year. So when we hold coins for a year and 1 day than the gain are tax free.
If you trading with your coins or sell it before the holding period is over, have have to pay 25% tax from your gain.