Conmoriencia: What Happens if Two People Die at the Same Time?

🇪🇸 Read the original in Spanish

Imagine a couple driving on the highway who suffer a fatal car accident in which both lose their lives instantly. Beyond the human tragedy, this event triggers a complex legal scenario in the field of inheritance and successions in Spain. Who inherits from whom if it cannot be determined who passed away first? The answer to this question not only defines the destination of the family estate but also prevents endless legal disputes between the heirs of both parties. In this article by AbogadoAI, we will analyze in depth the concept of conmoriencia (simultaneous death), its regulation in the Código Civil (Civil Code), the special provisions of regional laws, the practical procedures, and its massive tax impact.

What is conmoriencia and how is it regulated in Spain?

Conmoriencia is a legal fiction applied when two or more people, called to succeed one another (for example, parents and children, or spouses), die in the same event or under such close temporal circumstances that it is scientifically impossible to determine who died first.

Spanish law contemplates two theoretical ways to resolve this dilemma:

1. Premoriencia (predecease): This consists of establishing presumptions of survival based on age or sex (assuming, for example, that the younger person or the male survived longer). This was the system of classical Roman law.
2. Conmoriencia (simultaneous death): This consists of presuming that all persons died at the same time, meaning no transmission of inheritance rights takes place between them.

The framework of the common Código Civil

In Spanish common civil law, which applies to most of the national territory, the principle of conmoriencia rules. This principle is expressly enshrined in *Article 33 of the Código Civil***, which literally states:

> "If there is doubt, between two or more persons called to succeed each other, as to who among them died first, whoever alleges the prior death of one or the other must prove it; in the absence of proof, they are presumed to have died at the same time and no transmission of rights from one to the other takes place."

This article contains two fundamental rules:

• The burden of proof: Anyone who has an interest in proving that one died before the other (premoriencia) to alter the order of succession must provide irrefutable medical or forensic evidence.
• The presumption of simultaneity: If the priority of death cannot be proven, they are presumed to have died at the same time. Since there is no survival of one over the other (even if only for a second), neither of the deceased inherits from the other. The estate of each will go directly to their respective blood heirs or testamentary heirs, "skipping" the mutual transfer.

Special Provisions in Derechos Forales (Regional Civil Laws)

Spain has a multi-legislative legal system where common law coexists with derechos forales (regional or special civil laws) of certain Autonomous Communities. In matters of conmoriencia, there are important nuances you should know if the succession is governed by the civil law of Catalonia, Aragon, the Balearic Islands, Galicia, Navarre, or the Basque Country.

Catalonia: The 72-hour rule

The Código Civil de Cataluña (Civil Code of Catalonia) introduces a very specific and practical time rule to avoid litigation. In its Fourth Book (relating to successions), it establishes that if two people called to succeed each other die in the same disaster or under circumstances of common danger, they are presumed to have died at the same time.

However, it adds a golden rule: if they die within a time difference of less than 72 hours as a consequence of the same accident or cause, the presumption of conmoriencia also applies. In other words, even if it is proven that one survived the other by a few hours in the hospital, if the death occurs within that 72-hour window from the same cause, there will be no transmission of assets between them. This enormously simplifies the management of the inheritance and prevents a family's fortune from accidentally passing to the other family due to a difference of minutes in an ICU.

Navarre and Aragon

In the Autonomous Community of Navarre (governed by the Compilación del Derecho Civil Foral de Navarra or Fuero Nuevo) and in Aragon (Código del Derecho Foral de Aragón), a line similar to that of the common Código Civil is followed, based on the need to prove premoriencia. If it cannot be proven who survived, it is understood that they died simultaneously, and the successions are opened independently, ensuring that ancestral or family assets remain within the original family lines.

Step-by-Step Practical Procedures in Case of Conmoriencia

When a simultaneous death occurs, relatives must face a series of complex administrative and notarial procedures. Below, we detail the legal roadmap to follow:

Step 1: Obtaining the Certificados de Defunción (Death Certificates)

It is necessary to request the death certificates of all deceased individuals from the Registro Civil (Civil Registry). These documents will state the date and, as far as possible, the time of death. If the death occurred in an accident, the exact time appearing on the medical report or the forensic report will be crucial.

Step 2: Requesting the Certificados de Últimas Voluntades y Seguros (Wills and Insurance Certificates)

Once 15 business days have elapsed since the deaths, you must request the Certificado de Actos de Última Voluntad (Certificate of Last Will and Testament) for each of the deceased. This document will confirm whether they made a will and before which notary. You must also request the Certificado de Contratos de Seguros de Cobertura de Fallecimiento (Certificate of Insurance Contracts for Death Coverage) to check if there were active life insurance policies.

Step 3: Analysis of the wills or the declaración de herederos (declaration of heirs)

• If there is a will: an authorized copy must be requested from the corresponding notary's office. It will be necessary to analyze whether the testators foresaw premoriencia or conmoriencia through sustitución vulgar (standard substitution clauses, for example: "I appoint my spouse as heir, and in their absence or in case of premoriencia or conmoriencia, my children").
• *If there is no will (sucesión intestada / intestate succession): a notary must process an acta de notoriedad de declaración de herederos abintestato (notarial act declaring heirs intestate) to determine who the relatives with the right to inherit from each of the deceased are, applying the rule of Article 33 of the Código Civil* (no transmission between them).

Step 4: Inventory and valuation of assets

A detailed inventory of the assets, rights, and debts of each of the deceased must be made separately. This includes real estate, bank accounts, vehicles, and ajuar doméstico (household goods).

Step 5: Drafting and signing the escritura de partición de herencia (inheritance partition deed)

The heirs of both parties will go to the notary to sign the deeds of acceptance and allocation of the inheritances. Since conmoriencia applies, two independent partition documents will be prepared, avoiding the double transmission of assets between the deceased.

Step 6: Tax settlement and registration

The corresponding taxes must be settled within 6 months from the date of death, and subsequently, real estate assets must be registered in the Registro de la Propiedad (Property Registry).

Deadlines, Amounts, and Key Figures You Must Know

The succession process in cases of conmoriencia is subject to strict legal deadlines and costs that should be budgeted for properly:

• 15 business days: The mandatory waiting period from the date of death before you can request the Certificates of Last Wills and Life Insurance.
• 6 months: The legal deadline to file and pay the Impuesto sobre Sucesiones y Donaciones (ISD / Inheritance and Gift Tax). This period can be extended for an additional 6 months if requested within the first 5 months of the filing period.
• 72 hours: The minimum survival period required by the Código Civil de Cataluña so that the presumption of conmoriencia is not applied in deaths resulting from the same accident.
• Between 7.65% and 34%: The state tax rate for Inheritance Tax, although this percentage varies drastically depending on the Autonomous Community of residence of the deceased, with tax reliefs of up to 99% existing in territories like Madrid, Andalusia, or the Valencian Community for direct relatives.
• Limit of €100,000: The state tax allowance per kinship applicable to the taxable base of the tax for direct descendants under 21 years of age, and up to €16,000 for descendants over 21 years of age and spouses (significantly expandable depending on regional regulations).

Practical Examples of Conmoriencia

To understand the real impact of this legal concept, we will analyze two scenarios with very different figures and estate consequences.

Example 1: Married couple without children who die in a traffic accident (Common Law)

Let's imagine Carlos and Sofía, a married couple residing in Madrid, who have no children and have not made a will. Carlos's parents are alive, and Sofía's parents are also alive. Both die instantly in a car accident. Carlos's net estate amounts to €250,000 and Sofía's to €300,000.

• *Application of conmoriencia (Art. 33 Código Civil):* Since it cannot be proven who died first, they are presumed to have died at the same time. There is no transmission of rights between them.
• Succession outcome: Carlos's inheritance (€250,000) goes directly to his parents as legitimate intestate heirs. Sofía's inheritance (€300,000) goes directly to her own parents. The estate of each family-in-law remains perfectly separate.
• What would have happened if Sofía had survived for just 10 minutes and this was legally proven? Premoriencia would apply. Sofía would have inherited from Carlos. Therefore, Carlos's €250,000 would have passed to Sofía (with the corresponding tax settlement). Upon Sofía's death 10 minutes later, the entire accumulated estate of both (€550,000) would pass in its entirety to Sofía's parents. Carlos's parents would be left without any rights to their son's assets.

Example 2: Couple with a will and a sustitución vulgar clause

Luis and Marta jointly own 50% of an apartment valued at €180,000 (with an outstanding mortgage of €40,000) and a savings account with €30,000. They have a child together, Hugo. In their wills, both declared: "I appoint my spouse as universal heir, and in the event of premoriencia or conmoriencia, my son Hugo". Both die in a shipwreck.

• *Application of conmoriencia: As the presumption of simultaneous death operates, the sustitución vulgar* clause provided for in the will is immediately activated.
• Succession outcome: The son, Hugo, directly inherits 50% of his father's apartment and 50% of his mother's apartment, as well as all the savings, without double taxation occurring due to an intermediate transfer of assets from one spouse to the other. Hugo also assumes the mortgage debt of €40,000, which is deducted from the net value of the inheritance for tax calculation purposes.

Mistakes You Must Avoid

Managing an inheritance involving conmoriencia is highly delicate. Making a mistake can result in the loss of inheritance rights or severe tax penalties:

• Taking the time of death for granted without expert evidence: Trying to argue that one relative survived another based solely on speculation or the physical appearance of the body at the scene of the accident. Without a conclusive forensic or medical report, the courts will strictly apply Article 33 of the Código Civil.
• *Not planning for conmoriencia when drafting a will: Drafting a basic will where only the spouse is named as heir without including sustitución vulgar* clauses for cases of simultaneous death. This forces the opening of a costly and slow intestate succession to determine the substitute heirs.
• Settling Inheritance Tax as a double transfer when it does not apply: Paying taxes twice (from the first victim to the second, and from the second to the final heirs) when legally a conmoriencia has occurred. This represents an unnecessary tax expenditure of thousands of euros that is later complex to claim back from the regional tax agency.
• *Ignoring the vecindad civil (civil residence/status) of the deceased: Applying the rules of the common Código Civil* to a death that occurred in Catalonia or Aragon, ignoring regional specialties (such as the Catalan 72-hour rule), which can completely alter the legitimate destination of the assets.

Frequently Asked Questions (FAQ)

What happens to life insurance policies in case of conmoriencia?

If a married couple dies at the same time and each had a life insurance policy where the beneficiary was the other spouse, neither can inherit from the other when conmoriencia is applied. In this case, the life insurance payout is not lost: it is integrated directly into the estate of each insured person and passes to the legal or testamentary heirs designated in the second place.

How does conmoriencia affect joint bank accounts?

In the case of a joint bank account held at 50% by two people who die simultaneously, the bank will proceed to block 100% of the funds preventively until the inheritance deeds of both holders are presented. The heirs of each of the deceased will have the right to claim 50% of the balance existing in the account at the time of death.

Can the presumption of conmoriencia be legally challenged?

Yes. The presumption of conmoriencia established by Article 33 of the Código Civil is a iuris tantum presumption, which means it admits evidence to the contrary. Any legitimate interested party can go to court to try to prove, through forensic medical reports, vehicle telemetry data, autopsies, or qualified testimony, that one of the deceased survived the other by at least a few moments.

What happens to the primary residence if it was in both names?

If the primary residence belonged to both spouses in undivided halves, when conmoriencia is applied, half of the house will be transmitted to the husband's heirs and the other half to the wife's heirs. If the heirs do not match (for example, if they had no children and their respective parents inherit), the property will enter a state of proindiviso (joint ownership) between both families-in-law, who must agree to sell it or allocate it to one of the parties.

In Summary

• Conmoriencia is the legal presumption that two or more people called to succeed each other died at the same time if the contrary cannot be proven.
• It is regulated in *Article 33 of the common Spanish Código Civil*** and determines that there is no transmission of inheritance rights between the deceased.
• Catalonia has a specific regional rule that sets a minimum survival period of 72 hours to rule out conmoriencia in common accidents.
• It avoids double taxation, as the assets of each deceased person go directly to their heirs without passing through the estate of the other deceased spouse.
• It is essential to draft wills with sustitución vulgar clauses to clearly plan for these family catastrophe scenarios.
• The deadline to settle Inheritance Tax is 6 months from the date of death, extendable for another 6 months.

General legal information, not personalised legal advice. For your specific situation, ask your question for free at AbogadoAI — answers grounded in Spanish law (BOE), in English.

This is general information, not legal advice. Verify on the BOE or consult a lawyer for your specific case.