Obviously, a country which has regulations regarding bitcoin and tax it as capital gains, such as in US. https://www.investopedia.com/university/definitive-bitcoin-tax-guide-dont-let-irs-snow-you/
On the other hand, in a country where people could easily use bitcoin in daily transactions in Japan, there is no tax for trading bitcoin. https://cointelegraph.com/news/its-official-japan-has-eliminated-tax-on-bitcoin-rise-in-trading-expected
But in most countries that don't have any fixed regulations, you are free to trade bitcoin and don't have to pay tax, but only fees to exchanges.