Swapping to stablecoins: capital gain or neutrality?

The DGT’s position: an exchange between distinct assets

The DGT treats the exchange between distinct crypto-assets as a barter. This conclusion rests on the administrative doctrine on crypto barters —among others, V0999-18— and on Article 37.1.h of the Personal Income Tax Act.

In practical terms, this means that someone who converts 1 BTC —acquired at €10,000— into USDC when bitcoin trades at €80,000 realises a capital gain of €70,000, even though they have not left the crypto environment or withdrawn funds to a bank account. The transaction is taxed in the tax year of the swap.

The counter-arguments: economic function and international comparison

The DGT’s position is technically correct within the literal wording of the rule, but economically arguable. The argument against it is twofold.

First, the function as a substitute for money: a stablecoin referenced to a legal-tender currency has, by design, a stable value. Its acquisition produces no return different from that of holding the reference currency, so that swapping bitcoin for a stablecoin is, in essence, economically equivalent to swapping it for dollars. Second, the international comparison: in other jurisdictions, treatments closer to neutrality have been debated for certain currency-referenced tokens. Spain, as things stand, has not introduced an exception of that kind.

Our reasoned opinion

Until there is a legislative amendment or a different judicial criterion, the prudent position remains to treat the move from bitcoin or ether to a stablecoin issued by a third party as a barter with tax effect. What is arguable, in our view, is the legislative policy or the economic rationality of the result, rather than the direction of the administrative criterion in force. Anyone who wishes to depart from it in a self-assessment must be aware that they do so without doctrinal backing and assuming the corresponding risk.