What it regulates
Only property relations (article 31 of the Family Code): the regime of common and separate property, mutual maintenance, participation in the income, participation in the family expenses, and the property that each spouse receives at divorce.
What it cannot regulate
Personal non-property relations; the rights and duties towards the children; a limit on the right to apply to court; a limit on the right of a needy spouse who cannot work to receive maintenance; and terms that put one of the spouses in an extremely unfavourable position.
The form
Under article 30 of the Family Code, the written form and notarial certification are obligatory. If the notarial form is not kept, the transaction is invalid (article 112 of the Civil Code).
Changing the contract
The spouses can change or terminate the contract at any time by agreement, in the same form in which they made it. A unilateral refusal to perform it is not allowed. At the demand of one of the spouses, a court can change or terminate the contract on the grounds in the Civil Code (article 32).