Spain: Self-custody crypto outside Form 721 if private keys remain under owner control

# Form 721 and self-custody Spain's tax authority has confirmed that cryptocurrency held in self-custody wallets does not need to be reported on Form 721 so long as the taxpayer retains control of the private cryptographic keys and no foreign third party is safeguarding those keys. This treatment applies whether the wallet is hot (connected to the internet) or cold (offline). The deciding factor is custody and control of keys, not wallet type.

# The rule in practical terms Form 721 is the Spanish overseas asset declaration that covers qualifying virtual currency holdings held abroad. The rule covers virtual currencies when they are held by a person or entity that safeguards private cryptographic keys for third parties or otherwise maintains, stores, and transfers the assets. The reporting obligation applies to Spanish residents, certain legal entities, and designated permanent establishments.

If you keep your own private keys—whether on a hardware device, a software wallet you control, or another self-custodial method—those balances are not counted toward the Form 721 reporting requirement. If a third party outside Spain or a foreign entity is safeguarding the keys for you, those holdings can fall within Form 721 when the remaining conditions for reporting are met.

# How the authorities explained the test

# Thresholds and other procedural points

# Interaction with regulated platforms and DAC8 Movements between regulated trading platforms and self-custody wallets can produce records under DAC8 or other exchange reporting regimes, even when self-custody keeps balances outside Form 721. Transfers do not automatically convert a self-custodial balance into a foreign custodial holding, but transactions involving foreign custodians remain within the scope of reporting rules where the custody test is met.

# Takeaway for taxpayers If you retain and control your private keys, you generally do not need to include those holdings on Form 721. If a foreign third party holds or safeguards your keys, review whether the custodian and the balance meet the Form 721 conditions and the €50,000 threshold. The custody test is factual: who holds the keys matters more than whether a wallet is hot or cold.