When can I get a BBC?

I am paying tuition fees at another institution and am also studying at Leiden University:
If you have to pay statutory tuition fees at Leiden University (or an amount of money equivalent to the statutory tuition fees), then you can pay Leiden University with a BBC. You can request a BBC from the other institution at which you study.

I am paying tuition fees at Leiden University and am also studying at another institution: 
You can request a BBC to pay for the statutory tuition fees from the Front Office of the Student Affairs Department (Plexus). You can then submit the BBC to the other institution.