There are different regulations in each state as to when compulsory school attendance ends or when a pupil can be released prematurely from compulsory education upon application by the school board.
In Saarland, full-time compulsory education lasts nine school years. It ends at the latest with successful attendance at grade 9. For pupils who have not achieved a vocational education maturity within nine years at a community school, the general full-time compulsory at the request of the parents can be extended for one school year.
With the termination of the general full-time compulsory education begins the obligation to attend the vocational school. Compulsory attendance of a vocational school lasts three years. Independently, trainees are required to complete their vocational training until completion of the vocational training relationship (http://sl.juris.de/cgi-bin/landesrecht.py?d=http://sl.juris.de/sl/gesamt/SchulPflG_SL.htm)