A residence for studies in Spain can be changed to a residence and Work Authorization for an Employed Person. This modification procedure is included in article 199 of the Immigration Regulations. The requirements would be, among others:
1) Have been in Spain for at least three years with an authorization to stay for studies
2) Not having received a scholarship or subsidy from public or private organizations within Spanish cooperation or development programs or from the country of origin.
3) Have completed studies.
4) Have a job offer
This authorization will be processed as an initial authorization, valid for one year, and after this period you must renew your authorization.
In this way, once you have been in Spain for a certain period of legal stay as a student, you can change your student card to a residence and work permit.
Law Office INTRO