In Portugal, the principle of the immutability of prenuptial agreements and property regimes is one of the central rules of matrimonial law.

Set out in Article 1714 of the Civil Code, it establishes that, after marriage, agreements regulating the spouses’ property cannot be altered, apart from a few specific legal exceptions.

It is therefore important to pay special attention when choosing a property regime and/or drawing up a prenuptial agreement prior to the wedding.

What are prenuptial agreements and property regimes?

Before the wedding, the bride and groom can sign an agreement called a prenuptial agreement, in which they choose how the assets will be managed during the union. The options include:

• General community of property: all assets, current and future, become common;

• Communion of property: only property acquired after the marriage is shared;

• Separation of property: each spouse retains exclusive ownership of their property.

If the bride and groom do not sign a prenuptial agreement, the regime of communion of acquisitions automatically applies in Portugal.

The principle of immutability

Once the marriage is celebrated, the general rule is that the decisions made in the prenuptial agreement (or the supplementary regime chosen by law) cannot be changed. The purpose of this principle is to protect the stability of matrimonial relations, avoiding changes that could harm one of the parties or third parties, such as creditors.

Exceptions to the principle of immutability

Article 1715 of the Civil Code provides for some situations in which this rule can be relaxed, namely, but not limited to:

• Judicial separation of property: this can be decreed by the courts if there is poor administration of the joint property or a risk of loss of assets (for example, a spouse who incurs excessive debts or acts irresponsibly can put the estate in danger). After the judgment decreeing the judicial separation of property becomes final, the matrimonial property regime becomes that of separation, and the common property is divided as if the marriage had been dissolved;

• Judicial separation of persons and property: in exceptional cases, the spouses can apply to the Court or, if requested by both and by mutual agreement, to the Civil Registry Office, to change the regime, provided they can demonstrate that this is in the interests of the family and that third parties (such as creditors) will not be harmed. The judicial separation of persons and property allows the spouses to maintain their marital status, although they can live separately, suspending the effects associated with married life, such as the duty of cohabitation and assistance. The judicial separation of persons and property ends with the reconciliation of the spouses or the dissolution of the marriage. After the judgment decreeing the judicial separation of property becomes final, the matrimonial property regime becomes that of separation, and the common property is divided as if the marriage had been dissolved. The effects on property are retroactive to the date on which the action was brought, unless the court rules otherwise.

Differences between legal separation and divorce

Although legal separation and divorce have similarities, the main differences are:

• Maintenance of the marriage bond: In separation, the spouses remain married, while in divorce the bond is dissolved;

• Possibility of reconciliation: Separation can be reversed by agreement of the spouses, while divorce is final.

Judicial separation of persons and property continues to be a relevant tool in Portuguese law, offering an alternative for couples who wish to end their cohabitation without dissolving the marriage. Although less used than divorce, it remains important in contexts where the spouses have religious, property and social reasons for preserving the property bond.

Despite its rigidity, the principle of immutability has been debated in doctrine and case law, and some European countries have already relaxed their rules, allowing changes to the property regime during the marriage. For example, in Spanish, Italian, Belgian, German and Swiss law, the system of free changeability is in force, i.e. changing the property regime during the marriage does not require judicial control. However, in Portugal, the conservative view prevails, reinforcing stability as a priority. In other words, although there are exceptions for special situations, the rule is clear: what was decided before marriage must prevail, except in cases authorized by law.

It is essential to seek legal advice from experienced family lawyers to ensure that all parties have their rights protected.