Regulated Exchanges vs Self-Custody: The Tax and Security Decision in 2025
"Not your keys, not your coins" is the mantra of self-custody in crypto. But from a tax and regulatory compliance perspective in Spain, the decision between storing assets in a regulated exchange or in your own wallet has implications that go beyond technical security.
What is a regulated exchange and self-custody?
Regulated Exchange (Custodian)
An exchange licensed or registered with authorities (CNMV, Bank of Spain, or European equivalents):
- Stores your crypto in its wallets → you are the economic beneficiary but not the technical custodian.
- Examples: Coinbase (VASP registered in Spain), Bit2Me (with VASP), Binance (in the process of MiCA regulation).
- Reporting obligations: subject to Modelo 172 and DAC8 → automatically report balances and transactions of their Spanish clients to the AEAT.
Self-Custody
You hold your own private keys and control your wallet:
- Types: software wallet (MetaMask, Trust Wallet), hardware wallet (Ledger, Trezor), paper wallet.
- No one else controls your assets → maximum sovereignty.
- No automatic third-party reporting obligations → but YOU are responsible for declaring.
Tax Implications of Each Option
Regulated Exchange: Automatic Reporting to AEAT
When operating on a regulated Spanish exchange or one with a presence in Spain:
- The exchange automatically reports your balances (as of December 31) and transactions to Modelo 172.
- These details appear in AEAT's tax data → they may be pre-filled in the draft return.
- Withholding on income (staking rewards, interest) may be automatic.
Tax Advantage: Lower risk of forgetting or making errors in your declaration, as the data is already in AEAT's systems.
Disadvantage: Less privacy, greater exposure during inspections.
Self-Custody: Full Responsibility on the Taxpayer
With self-custody:
- No one reports to AEAT on your behalf → you are solely responsible for accurate declarations.
- No pre-filled data in the draft return → higher risk of errors or omissions.
- DeFi transactions are particularly complex to track manually.
- Tools like Koinly, DeGenTax, or Rotki connect to your wallets via API and calculate IRPF.
Tax Advantage: If you never connect your wallet to exchanges with KYC, AEAT has very limited direct information about your assets.
Disadvantage: The declarative responsibility falls 100% on you. If AEAT conducts an inspection and detects inconsistencies (fund movements between exchanges and wallets), you could face significant regularizations.
Modelo 721 (Cryptocurrencies Abroad)
Both options may require Modelo 721:
- If you hold crypto outside Spain (exchange or wallet) with a total value > €50,000 → you must file Modelo 721 (analogous to Modelo 720 for crypto).
- Applies to both foreign exchanges and hardware wallets outside Spain.
- Self-custody in a hardware wallet abroad (e.g., physically located in another country) → might require Modelo 721.
The key to Modelo 721 is the "custody" of the crypto, which in self-custody is always yours regardless of where the device is physically located.
Security of Each Option: Balancing with Tax Risk
| Factor | Regulated Exchange | Self-Custody |
|---|---|---|
| Exchange hacking risk | High (history: FTX, Celsius) | Low (if hardware wallet) |
| Key loss risk | None (recoverable) | High (irrecoverable seed phrase) |
| Regulatory risk | Low (regulated exchange) | Medium (evolving rules) |
| Automatic AEAT reporting | Yes | No |
| Inheritance access | Easy | Requires planning |
| AEAT seizure | Easy for AEAT | Complex for AEAT |
Hybrid Strategy: The Best of Both Worlds
The most common strategy for significant crypto holdings:
- Liquid portion (for trading) → regulated exchange with KYC. Facilitates declaration and has automatic reporting.
- Long-term portion (HODL) → hardware wallet in self-custody. Greater security and control.
- Meticulous record-keeping of all movements between the exchange and the self-custody wallet → these are transfers between your own wallets (not taxable events) but must be documented.
Wealth Tax: Where Are My Cryptos?
For Wealth Tax, you must declare the value of YOUR crypto as of December 31, regardless of whether it is in an exchange or a wallet:
- Exchange: the value is the balance in EUR according to the December 31 rate.
- Own wallet: the market value of the crypto as of December 31.
Location does not exempt you from the Wealth Tax obligation.
CBDC and the Future of Custody
The digital euro (CBDC, central bank digital currency) could change the custody landscape:
- CBDCs will be held by the central bank or intermediary banks → always institutional custody.
- There will be no real self-custody of CBDCs (by ECB design).
- This contrasts with Bitcoin and adds additional value to self-custody of "uncontrolled" crypto.
Updated: April 2026 | Fiscal Year: 2025