The matrimonial property regime is chosen by the spouses. In Spain there are three economic regimes: joint property, separation of property and participation regime. If the spouses do not say anything, the joint property regime will be applied by default, except in some autonomous communities where the separation of property regime is applied.
Roughly speaking, in the community property regime, each spouse retains his or her private assets (what he or she had before the marriage) from the marriage onwards, only those private assets are increased by free title and the community property begins to form (all the work income they have spam database from the marriage onwards, everything that those assets produce in interest and all the private income and interest will be community property); in the separation of property regime , each spouse retains his or her private assets, but this does not exempt the spouses from purchasing assets in co-ownership and contributing to the expenses of the marriage; and finally the participation regime : it works like the separation of assets and when it is liquidated, there is a participation in the profits. The initial and final assets are taken into account to calculate the profit.
The matrimonial property regime is governed by the principle of freedom of stipulation in the marriage contract, that is, the property regime will be the one agreed upon by the spouses ( article 1315 of the Civil Code). The principle of mutability also applies; spouses can modify their property regime as many times as they want or can. But this freedom to modify the regime has limits: it cannot affect third parties, article 1317 of the Civil Code, and rights already acquired by third parties cannot be affected.
Marital property is property that belongs to the community property, that is, to the members of the marriage.
Private property is property that belongs exclusively to one of the spouses.
Differentiating between one type of property and another is important, not only if the property regime is liquidated but also if it is extinguished by the death of one of the spouses.
To determine whether an asset is separate or joint property, the moment in which the assets were acquired must be taken into account and it will depend on the origin of the assets . For example, assets acquired by inheritance are separate property of the spouse who inherited.