The tax is only on the gains of the worth of the spend Bitcoin. If you buy a Bitcoin and immediately spend it on something, there will be no gain, so $0,00 taxe

The tax is only on the gains of the worth of the spend Bitcoin. If you buy a Bitcoin and immediately spend it on something, there will be no gain, so $0,00 taxes. If you bought a Bitcoin when it was $5000 and you spend 0.2 Bitcoin today (now they're ~$10000 a piece) you would need to report $1000 of capital gains. You could argue that would make your 0.2 Bitcoin / $2000 purchase cost more, because you have to add the tax. On the other hand, if you sell those Bitcoin later, you would have to pay those capital gains tax anyway. The story does become a bit more complex when you factor in long-term vs short-term capital gains tax.