As I understand it, it is not a debenture as such it is called a Corporate Surety Scheme. A non refundable surety. It is only applicable to ESF schools (subsidised) not ESF educational services (private - the ones set up to generate profits for ESF schools). The scheme is for expats relocating to HK and the student must be a native english speaker and it is conditional on passing an english proficiency and interview. In regards to debentures, there are so many different types for the various schools, some are refundable, some start to deppriciate as soon as you purchase them even if your child does not yet have a place at the school and some are non refundable. Best to check them out with the schools you are applying to.