According to CoinMeta, Spain's Modelo 721 regulations emphasize key controls rather than the size of investment portfolios. According to the latest ruling by the Spanish Tax Authority, large self-held crypto asset portfolios may not fall under the scope of Modelo 721 at all, while small amounts of assets held through foreign custodians may trigger reporting obligations. These regulations originate from Royal Decree 1065/2007, which requires Spanish taxpayers to report on foreign virtual currencies when their assets are held by certain entities. The decree stipulates that if the asset balance as of December 31 of each year does not exceed 50,000 euros, no reporting is required. Once this threshold is exceeded, all eligible virtual currencies must be reported. Self-holding changes the analysis, as there is no third-party custodian to protect taxpayers' private keys. The Spanish Tax Authority confirms in the Modelo 721 guidelines that private keys controlled by taxpayers are not included in the balance used for reporting on foreign cryptocurrencies.