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In my opinion all the earnings should be taxed no matter of crypto or fiat earnings or it will leads to illegal activities like money laundering,tax fraudulent etc.But many coutires don't know how to put regulations on the crypto currencies that is why they are afraid to accept it legally so we need to move upfront and pay the appropriate taxes by ourselves to make the bitcoin legal in your country.
Well you probably shouldn't pay blindly either lol.
The reason why Philippine citizens have to pay taxes on crypto earnings despite an absence of regulations is because they have an obligation to pay income tax. Legally, any and all income from any source should be reported and paid the appropriate amount of tax for. Generally, anyone who pays income tax should pay taxes for their crypto earnings even if their country doesn't have any crypto regulations.
There are a few places that don't oblige residents to pay income tax, so unless there are specific regulations for crypto, their residents might not need to pay taxes for their crypto earnings.
Not legal advice, just sharing.