You probably don't have to, just like you don't have to tell the government how many bitcoins you're holding. In most countries you only owe income tax if you convert your coins to fiat. And it doesn't matter if you juggle between currencies to ultimately end up back in crypto. The moment you convert to fiat you owe taxes, and it doesn't mater if you go back to crypto later on.
There are also extreme cases of governments wanting people to pay taxes on held coins, or asking additional taxes like VAT or 1% of every transaction, but those are rare. For instance Australia used to charge VAT, but they don't anymore.