This information concerns only Italian residents. All capital gains for the year must be calculated because they are taxable and must be declared. For the purposes of verifying that the threshold of €51,645.38 is exceeded, the amount of the investment must be determined using, as the cryptocurrency price, the price recorded at the beginning of the year. Thus, for example, for the purpose of establishing the taxability of capital gains for 2020 (Unico 2021 declaration to be filed by 30 September 2021) the conversion into Euros of the amounts of cryptocurrencies held during 2020 must be made on the basis of the crypto prices on 1 January 2020. This information is taken from the e-book 'Aspetti fiscali: Criptovalute e Bitcoin' edited by Dr. Giorgio D'Amico, available at this link.