In the Spanish Building Planning Law, the Designer is one of the building agents contemplated. It is the agent who, on behalf of the developer "Promoter (building agent)") and subject to the corresponding technical and urban planning regulations, drafts the project.

Other technicians may draft "partial projects" of the project, or parts that complement it, in coordination with the author of the project. When the project is developed or completed through partial projects or other technical documents, each designer will assume ownership of their project.

The obligations of the designer are: