What makes housing levy susceptible to corruption

The demand for houses in Nairobi has pushed residential owners to build storey buildings to help bridge the deficit. [Phillip Orwa, Standard]

Proper housing is a necessity for all of us. But when the national government first announced its housing policy and specifically the Housing Levy, I feared for the employee and the employer.

Somebody was to fund this project. The more worrying aspect of this venture is that workers and businesses are levied first, then the housing comes later. Such a model is susceptible to corruption.