I've heared that in some countries people have to pay the income tax after buying fiat for their bitcoins. Anyone faced such problem? If yes then how you deal with it in your country?
At one point of view bitcoin is an instrument for investment so ppl buy it willing to get income in their currency.
At the other point it is a currency and it might be used with a purpose of saving. In this case the tax would be stupid.
It depends on the ruling of your country, any object can be tax whatever form, bitcoins on the other hand can be taxed as you exchange it to your local currency or the gains from the change of its value depending on the ruling.
Good thing we don't have tax in using bitcoins yet here.