“Actio Nata” and Tax Refunds After Acquittal: A Supreme Court Shift in the Taxpayer’s Favor

“Actio nata” and Tax Refunds After Acquittal: A Supreme Court Shift in the Taxpayer’s Favor

The Spanish Supreme Court’s Third Chamber has established an important practical and legal doctrine on the refund of undue tax payments linked to criminal proceedings. The limitation period does not necessarily start when the payment is made. It starts when the taxpayer can effectively exercise the right to claim—particularly when a final acquittal establishes that the payment was undue. This application of the actio nata principle strengthens legal certainty and protects taxpayers from unjustified delays by the authorities.

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1. What problem does this doctrine solve?

Article 66(c) of Spain’s General Tax Law (Law 58/2003) sets a four-year limitation period for requesting a refund of undue payments, counted from the day after the right to request the refund could be exercised. The Tax Agency has traditionally treated the payment date as the starting point. That can be unfair when a criminal investigation suspends the tax proceedings and the taxpayer cannot yet establish that the payment was undue.

A typical scenario

• A taxpayer pays an amount during a tax inspection.
• The Tax Agency suspects a tax offence and refers the case to the Public Prosecutor, suspending the administrative proceedings.
• The criminal case ends with a final acquittal, without a finding that the payment was owed.
• The Tax Agency argues that the refund claim is time-barred because more than four years have passed since payment.

Can the taxpayer still claim a refund? Yes. The limitation period does not begin with the payment if the taxpayer could not yet exercise the claim. It begins when the taxpayer can claim with legal certainty that the payment was undue—in this case, when the acquittal becomes final. That is the practical meaning of actio nata.

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2. Legal basis and Supreme Court doctrine

The Supreme Court’s case law, including Judgment No. 1063/2025 of 21 July 2025 (ECLI:ES:TS:2025:3723), applies actio nata to the start of the limitation period for refunds where:

1. The payment could not be regarded as undue when it was made because its status was uncertain or depended on ongoing criminal proceedings; and
2. It became unmistakably undue only after a final decision—in this case, a final acquittal—confirmed that status.

The Court’s reasoning is that a claim does not exist in an exercisable form until the legal position is sufficiently clear. Under actio nata, the right arises when the corresponding legal action can actually be brought.

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3. Why is this approach fair and legally sound?

a) Good administration

A taxpayer’s right to claim should not be penalised by the authorities’ own conduct. Referring a case to the Public Prosecutor prevents the taxpayer from pursuing the refund until the criminal case has concluded.

b) Effective protection of rights (Article 24 of the Spanish Constitution)

The doctrine protects effective judicial protection and the taxpayer’s legitimate interests. A right should not expire merely through the passage of time when it could not be exercised for reasons beyond the taxpayer’s control.

c) Legal certainty and the prohibition on unjust enrichment

The actio nata approach prevents the Tax Agency from retaining money that was not owed and aligns the limitation period with the point at which the payment is established as undue with legal certainty.

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4. Practical implications for taxpayers

• Four-year period: under Article 66 of the General Tax Law, it runs from when the taxpayer can know and claim that the payment was undue, not necessarily from the payment date.
• Criminal proceedings: where they prevent certainty about whether the payment was owed, they can affect when the refund claim becomes exercisable.
• No premature time-bar argument: the Tax Agency cannot rely on expiry if the taxpayer could not exercise the refund right before learning of the final acquittal.

The same reasoning may apply where the undue nature of a payment depends on an external decision, provided that the taxpayer could not exercise the right before that decision was known.

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5. Conclusion: a case-law development with real impact

Applying actio nata to refunds following a criminal acquittal is a meaningful step in protecting taxpayers’ rights. The Supreme Court has confirmed that the limitation period for reclaiming an undue payment starts when the right can effectively be exercised, rather than automatically on the payment date. This strengthens legal certainty, prevents taxpayers from losing rights because of delays outside their control, and brings tax rules into line with general legal principles and the conclusion of criminal proceedings.

In short, actio nata gives taxpayers a practical way to defend their rights without being trapped by an unfair or premature limitation period.

Read the original article in Spanish.