Base from my recent post "Does bitcoin could be call a job?" I have read your opinions regarding to that. Doing these things is a form of earning money basically we have income. So does it need to be taxed? Because this is also a source of income, and we might call it as a job?
Depends on (a) your local government and (b) the amount and type of income.
In some countries, under certain circumstances, there's no tax on capital gains on Bitcoin. However if you accept bitcoins as a form of payment, depending on the amount, you very likely will have to file it as part of your tax report.
I guess if there is a capital gain tax in the country, gains from bitcoin fall under tax. When we talk about capital gain, taxation happens when the gain is realized - that is when the capital asset is sold. When you sell bitcoins for USD that you receive on your banking account, you can be asked about the origin of the money. The question is, how can the government estimate your real gains from bitcoin: what was your cost of mining that can be deducted from the revenue received from selling it for USD. I'm sure very soon they will try to come up with a methodology of some sort.