Unlike natural persons, whose legal personality and legal capacity are attributes inherent in their very existence, in the case of legal persons in general, and companies in particular, it is the legal system that determines the scope of their legal personality, recognises their ability to participate in legal dealings as separate subjects of rights and obligations and, ultimately, makes their legal existence possible.

It follows that there is no absolute freedom in the creation and configuration of companies. Rather, given their potential impact on legal dealings, and in the interests of safeguarding legal certainty and protecting the interests of third parties, each legal system offers a choice among the different legal forms — numerus clausus — that it establishes.

Under Spanish law, a company exists and produces legal effects from the moment the parties agree to form it, provided that they have not confined those effects, by agreement, to a purely internal sphere.

Where the legislature imposes special formal requirements for the formation of a company and establishes a specific system of registration and publicity for companies so formed, compliance with those requirements merely determines that the company acquires the intended legal status, since its legal personality exists from the very moment of its formation.