Tax Prescription in Spain: When the AEAT Can No Longer Pursue You

The Four-Year Limitation Period: Article 66 LGT

Spanish tax law provides a general limitation period of four years within which the tax authority — the Agencia Estatal de Administración Tributaria (AEAT) — must exercise its rights. This is established by Article 66 of the Ley General Tributaria (LGT), Spain's fundamental tax procedure statute.

The four-year clock applies to four distinct rights: (1) the AEAT's right to determine the tax debt through an assessment; (2) the AEAT's right to demand payment of a previously assessed debt; (3) the taxpayer's right to request a refund of taxes overpaid; and (4) the taxpayer's right to obtain recognition of a tax credit or benefit. For the purposes of this article, we focus primarily on the first two — the AEAT's right to investigate and assess underpaid tax.

The starting point for the prescription clock is the day after the end of the voluntary filing period for the relevant tax return. For IRPF (personal income tax), that deadline is 30 June of the year following the tax year — so for IRPF corresponding to the 2021 fiscal year, the voluntary filing period ends on 30 June 2022, and the four-year prescription clock begins on 1 July 2022, expiring (absent interruptions) on 1 July 2026.

What Interrupts Prescription

Prescription is not automatic or irrevocable. The four-year clock can be interrupted — reset to zero — by specific events. When prescription is interrupted, the full four-year period begins again from the date of the interrupting act. The interrupting events are:

• Any action by the AEAT notified to the taxpayer — this includes: a requerimiento de información (information request), the formal opening of a comprobación limitada (limited audit) or inspección (full inspection), the issuance of any draft assessment or notice of initiation of penalty proceedings, or any written communication that advances the verification process
• Any appeal or legal challenge by the taxpayer — filing a recurso de reposición, a reclamación económico-administrativa before the TEAR, or a judicial appeal before the Tribunal Contencioso-Administrativo all interrupt prescription for the period covered by the appeal
• Any act of the taxpayer that acknowledges the tax debt — this includes voluntary payment (even partial), filing a supplementary return (declaración complementaria), or any other communication that amounts to recognition of the outstanding liability

The interruption mechanism means that a single AEAT information request — even if it asks only for documentary information and does not itself constitute a formal assessment — resets the full four-year clock. Many taxpayers are unaware of this: they receive what appears to be a routine letter from the AEAT and assume it does not affect prescription, when in fact it has restarted the limitation period entirely.

The Practical Timeline: When Does Old Income Become Safe?

Working through the mechanics for a concrete example: suppose a Spanish tax resident failed to declare €100,000 of rental income from a Swiss property in their 2020 IRPF return.

• The 2020 IRPF voluntary filing period ended on 30 June 2021
• The four-year prescription clock started on 1 July 2021
• Absent any interruption, the AEAT's right to assess expires on 1 July 2025
• If the AEAT sends a routine information request about foreign accounts in March 2024, the clock resets, and a new four-year period runs from March 2024 — expiring in March 2028

The problem, in practice, is that the AEAT receives CRS (Common Reporting Standard) data from Switzerland covering 2020 fiscal year accounts in 2021. It may take several years to process and cross-reference this data against IRPF filings — but once it issues any notification to the taxpayer, prescription is interrupted and the AEAT has a fresh four years to complete the assessment. Prescription provides a theoretical safety net that CRS data exchange and modern information processing make increasingly difficult to rely upon.

Prescription of the Right to Inspect vs Prescription of the Debt

An important technical distinction: the four-year prescription period governs the AEAT's right to determine the tax debt (i.e., issue an assessment). Once a debt has been formally assessed and notified to the taxpayer, a separate four-year period governs the AEAT's right to collect that assessed debt.

Practically, this means that a tax debt does not simply disappear after four years from the tax year in question. If the AEAT issues an assessment in year four, the collection right runs for a further four years from the assessment date. A taxpayer could theoretically have a debt assessed in June 2026 relating to 2022 income, and the AEAT would then have until June 2030 to collect it — representing up to eight years from the original tax year before the matter is fully extinguished.

Extended Periods: The Modelo 720 Exception

The general four-year rule is subject to a significant exception relevant to taxpayers with undeclared foreign assets. Under the original Modelo 720 regime (the foreign asset declaration introduced in 2012), undeclared foreign assets were treated as ganancias patrimoniales no justificadas — unjustified wealth gains — and were assessed without any prescription period, regardless of when they arose.

This unlimited prescription provision was struck down by the European Court of Justice in its January 2022 ruling (Commission v Spain, Case C-788/19) as incompatible with EU law (the free movement of capital). Spain subsequently amended the law in response — the penalty-free declaration window and the unlimited assessment period were removed for EU/EEA assets.

However, for third-country assets (i.e., assets outside the EU/EEA — including the US, Switzerland, UAE, Singapore, and most offshore financial centres), Spain's amended legislation introduced a 10-year prescription period for IRPF and IS income linked to undeclared foreign assets. This represents a dramatic extension compared to the general four-year rule and means that income from undeclared non-EU/EEA assets remains assessable for a decade.

The Modelo 720 Late-Filing Trap: Clock Reset on IRPF

A particularly dangerous and counterintuitive consequence of Spain's prescription rules affects taxpayers who file a late Modelo 720. The Modelo 720 is a reporting form — it does not itself create a tax liability. However, it is closely linked to IRPF reporting obligations.

When a taxpayer files a late Modelo 720 — disclosing, for example, a Swiss bank account that should have been declared in the original 2021 filing — the late filing constitutes an act of the taxpayer that acknowledges the existence of the asset and may restart the IRPF prescription clock for all years in which that asset generated income.

Concretely: if you file a late Modelo 720 in 2025 disclosing a Swiss account that generated interest income from 2018 onwards, and the IRPF prescription period for 2018 income would otherwise have expired in 2023, the late Modelo 720 filing may be treated as an act acknowledging relevant facts that restarts the IRPF investigation right — potentially bringing 2018 income back into scope.

This is one of the most important reasons why voluntary regularisation of foreign asset positions must always be structured carefully, with legal advice, rather than simply filing missing forms. The sequencing and framing of any voluntary disclosure materially affects the prescription consequences.

Tax Fraud: When There Is No Prescription

Prescription does not apply to criminal tax fraud. Under Article 305 of the Spanish Código Penal, a tax fraud offence is committed when a taxpayer defrauds the tax authority of more than €120,000 per tax per year through intentional conduct (false declarations, document falsification, deliberate concealment). The standard criminal limitation period — not the tax limitation period — applies, and for tax fraud this is typically five years under Article 131 of the Código Penal (ten years for aggravated fraud involving amounts over €600,000 or use of offshore structures).

Critically, the criminal investigation can be opened even where the administrative four-year IRPF prescription period has already expired. If the AEAT refers a case to the Ministerio Fiscal (public prosecutor) for criminal investigation, administrative prescription does not bar the prosecution. This creates a risk that a taxpayer who believes old tax years are prescribed may still face criminal proceedings — particularly where the undeclared amounts exceed the €120,000 threshold in any single year.

Regional Taxes: ISD and ITP Follow the Same Four-Year Rule

Inheritance and gift tax (Impuesto sobre Sucesiones y Donaciones, ISD) and property transfer tax (Impuesto sobre Transmisiones Patrimoniales, ITP) are regional taxes administered by the autonomous communities rather than the AEAT. Both follow the same general four-year prescription framework under Article 66 LGT, applied by the regional tax authority. The same interruption rules apply.

One practical issue: ISD on inheritances is frequently underdeclared because of the complexity of valuing assets, particularly real estate. Where assets are declared at below-market value, the regional authority has four years from the voluntary filing deadline to issue a revised assessment. The Hacienda autonómica (regional tax authority) has its own data and valuation tools — including cadastral values, real estate market data, and information received through notarial records — to identify undervaluations.

Prescription Scenarios at a Glance

Voluntary Regularisation: The Prescription Calculus

The most important practical application of prescription analysis is in voluntary regularisation decisions. When a taxpayer with undeclared income or assets considers coming forward voluntarily, two competing considerations bear on the prescription analysis:

First, if the relevant tax year has already prescribed, a voluntary declaration for that year will restart the prescription clock and bring the year back within the AEAT's assessment window. A voluntary disclosure is itself an interrupting act. This means that a taxpayer who voluntarily regularises for years that would have prescribed in the absence of action may paradoxically expose themselves to more assessment risk than if they had done nothing.

Second, the risk of criminal proceedings — which are not subject to administrative prescription — must be weighed against the benefit of prescription. For material underpayments (over €120,000 per year), criminal exposure does not extinguish with administrative prescription, and voluntary regularisation before a criminal investigation opens remains the only effective way to mitigate criminal risk.

The conclusion is that prescription analysis must be integrated with a broader regularisation strategy. There is no single answer applicable to all cases — the optimal approach depends on the amounts involved, the years at issue, the evidence the AEAT may already hold through CRS or other channels, and the individual's risk tolerance.

Does CRS Receipt Count as AEAT Action That Interrupts Prescription?

This is one of the most frequently asked questions in this area — and the answer is nuanced. The mere receipt of CRS data by the AEAT does not itself interrupt prescription. Prescription is interrupted only by acts that are notified to the taxpayer. An internal administrative act that the AEAT carries out without the taxpayer's knowledge — including receiving and processing CRS data from foreign financial institutions — does not restart the clock.

However, the significance of CRS data lies in what it enables: once the AEAT has received information that allows it to identify an underpayment, it can initiate a procedure — and the first notification of that procedure (typically a requerimiento) is the interrupting act. The AEAT's information processing capacity has improved substantially in recent years, and the time between CRS data receipt and AEAT action has shortened.

The practical lesson is that prescription should not be relied upon as a primary defence strategy in cases where the AEAT is likely to have received CRS data about the relevant accounts. The question is not whether prescription has technically run, but whether the AEAT has already been triggered to act — and a careful analysis of what information the AEAT likely holds, and what procedure it may already have started, is essential before any reliance on prescription.