According to CoinMeta, the Spanish tax authorities have confirmed that when the holder controls their private keys personally and the assets are not held by overseas third parties, the encrypted assets in a self-managed wallet do not need to be declared on the 721 form. This regulation comes from a binding response issued by the tax authorities on April 21. The 721 form is applicable to virtual currencies held overseas by institutions that manage private keys on behalf of others, and the criterion for determination is based on who holds control over the private keys. Both hot and cold wallets are treated equally under this framework, with a threshold of 50,000 euros.