It depends on where you're from. It's best to always report it when you're doing your taxes just to be safe and be sure you won't run into those kinda of problems of having to pay back.
can you mention any place where people pay taxes on bitcoin. i think still there is not a single country who have imposed tax on bitcoin. it is still tax free and the reason is that still not a sing le country legalize bitcoin.
What?
In the USA every single Bitcoin sale is taxable as a capital gain.
The IRS has ruled that Bitcoins are just like any other stock or property: you pay the capital gains tax on the difference between what you bought it for (the basis) and what you sold it for.
If you sell it for a loss then you can figure those losses against your gain just like any stock purchase and sale.
The difference between long term and short term capital gains also applies to Bitcoin sales.