Main supervisor and second supervisor(s)
Your PhD project will be overseen by one main supervisor and at least a second supervisor. Both supervisors must be appointed right at the start of your PhD track.
Your main supervisor will guide you and support you in all aspects of your research, will monitor your training needs as well as your progress, and will lead you through the process of producing the thesis and its examination. They will also advice you and help you in your career before and after graduation.
The second supervisor can have different degrees of involvement in your PhD project, from being an informal advisor to acting as co-supervisor side by side with your main supervisor. The second supervisor may be an external researcher from a different university.
On the Code of Practice for supervisors you can find a more detailed description of the roles and responibilities of your main and second supervisor.
Note on conflicts of interest. Family members of the supervisor or co-supervisor or other individuals whose relationship to the supervisor or co-supervisor could give rise to suspicions of partiality may not be appointed as supervisors, co-supervisors, voting members of the Doctorate Committee, guest experts, guest opponents, referees, or chairperson of the Doctorate Committee.
Finally, you and your supervisors are jointly responsible for ensuring that you can realistically finish your PhD track within the agreed time. Your supervisors are expected to inform the ILLC immediately of any problems that could potentially hinder you completing the PhD track within the given time frame.
In order to obtain a PhD degree, you need a so-called promotor. However, in the Netherlands, not all professors have the right to be a PhD promotor (ius promovendi). All full professors have this right. Associate professors can be granted ius promovendi on an individual basis, depending on their experience as co-promotor and supervisor. Assistant professors can be granted ius promovendi on an ad hoc basis for a specific PhD candidate, depending on various criteria.
If none of your supervisors has been granted ius promovendi, another professor who does have this right will need to be appointed as promotor. Your main supervisor and co-supervisor(s) will officially be called co-promotors. You may have a maximum of two promotors and two co-promotors. The role of the promotor can range from fully involved supervisor to purely administrative. Your main supervisor, co-supervisor(s) and promotor will agree on the extent to which each of them will be involved in the actual supervision of your research. The degree of involvement of each member of your supervision team should be described in your Training and Supervision Plan, so that this is clear from the beginning for all parties.
In those rare cases when it is not clear at the start of your PhD track who can act as your promotor, the institute director can be designated promotor: this is a temporary and purely pro-forma role, to comply with the administrative regulations for admission. In this case, you and your supervisors should agree who is to be your actual promotor by the start of the third year, at the latest.
If you want to know whether at least one of your supervisors has been granted ius promovendi, you'll just have to ask them.