Spanish inheritance tax deadline calculator

How this is calculated

The dates follow the Reglamento del Impuesto sobre Sucesiones y Donaciones, approved by Real Decreto 1629/1991. The Spanish sentences below are copied from the consolidated text on boe.es. The English line under each is our paraphrase, not an official translation.

1. Filing and payment: six months

Cuando se trate de adquisiciones por causa de muerte, incluidas las de los beneficiarios de contratos de seguro de vida, en el de seis meses, contados desde el día del fallecimiento del causante o desde aquel en que adquiera firmeza la declaración de fallecimiento.

In English: for acquisitions on death, the return is due within six months, counted from the day of death (or from the day a declaration of death becomes final).

[…] procediendo a ingresar su importe dentro de los plazos establecidos en el artículo 67 de este Reglamento para la presentación de documentos o declaraciones o en el de prórroga del artículo 68 […]

In English: when the tax is self-assessed, it is paid within those same periods, or within the extension.

2. The extension (prórroga): who, how long, by when

La oficina competente para la recepción de los documentos o declaraciones podrá otorgar prórroga para la presentación de los documentos o declaraciones relativos a adquisiciones por causa de muerte por un plazo igual al señalado para su presentación.

In English: the tax office may grant an extension equal in length to the filing period, that is, six months.

La solicitud de prórroga se presentará por los herederos, albaceas o administradores del caudal relicto dentro de los cinco primeros meses del plazo de presentación […]

No se concederá prórroga cuando la solicitud se presente después de transcurridos los cinco primeros meses del plazo de presentación.

In English: the heirs, executors or administrators must apply within the first five months of the filing period. An application made after that gets no extension.

La prórroga concedida comenzará a contarse desde que finalice el plazo de seis meses establecido en el artículo 67.1, a), y llevará aparejada la obligación de satisfacer el interés de demora correspondiente hasta el día en que se presente el documento o la declaración.

In English: a granted extension starts when the six months end, and late-payment interest is due until the return is filed.

Transcurrido un mes desde la presentación de la solicitud sin que se hubiese notificado acuerdo, se entenderá concedida la prórroga.

In English: if the office has not notified a decision one month after the application, the extension is treated as granted.

3. How the tool counts months

The Regulation says “seis meses, contados desde el día del fallecimiento” but does not say how a month is counted. The tool uses the general rule of the Civil Code:

[…] si los plazos estuviesen fijados por meses o años, se computarán de fecha a fecha. Cuando en el mes del vencimiento no hubiera día equivalente al inicial del cómputo, se entenderá que el plazo expira el último del mes.

In English: months run from date to date. If the month where the period ends has no matching day, the period ends on its last day. The General Tax Law (art. 7.2) makes the general rules of administrative law and the common-law provisions supplementary in tax matters, which is why this tool applies that rule. It is our reading, not a statement in the Regulation.

• Filing deadline = the date of death plus six months.
• Last day to request the extension = the date of death plus five months.
• Extended deadline = the filing deadline plus six months.

Example: death on 10 March 2026 gives 10 September 2026 for filing and payment, 10 August 2026 as the last day to request an extension, and 10 March 2027 if it is granted. Death on 31 August 2026 gives 28 February 2027 for filing, because February has no 31st; the last day to request is 31 January 2027.

Where two readings differ. When the date of death is the 29th, 30th or 31st and the six-month date was pulled back to a shorter month, “a further six months from the end of the first six” ends earlier than “twelve months from the date of death”. Article 68.6 says the extension “comenzará a contarse desde que finalice el plazo de seis meses”, so the extension runs six months from the end of the first period, counted date to date (Ley 39/2015, art. 30.4). The tool shows that earlier date, which is safe under either reading, and names the later one when the two differ.

4. Non-working days

Articles 67 and 68 do not mention weekends or holidays. The general rule for administrative procedures is:

Cuando el último día del plazo sea inhábil, se entenderá prorrogado al primer día hábil siguiente.

In English: if the last day of a period is a non-working day, it moves to the next working day. This applies to tax deadlines as a supplementary rule (Ley General Tributaria art. 7.2), and the Catalan tax agency applies it to the inheritance tax period. Only Saturdays, Sundays and Spanish public holidays count; holidays where the heir lives abroad do not, and for online filing the local-holiday rule in art. 30.6 does not apply (art. 31.3). The tool shows the plain date and warns when it is a Saturday or Sunday. Filing by the date shown is always safe, and for the extension request it is the only safe course.