I have a problem in understanding how bitcoins profits should be taxed in Finland. It looks like that only capital gain is taxed, whereas losses are not deductible. Suppose that I have an account on mtgox.com, I buy a bitcoin at 50$, I sell it at 300$, then I buy it again at 300$ and sell it again at 50$, should I be taxed for 250$ profit (even though the final actual profit is zero)?
In any case, how can the tax office trust my (fairly complicated) declaration?
I don’t think anyone can give you straight answer for that. Of course you can authenticate transactions you’ve made but nobody can tell for sure how many trades you’ve made in total, especially in mtgox for example.
In any case, I think taxation rules for bitcoin in Finland are a sketch at the moment.