As I just mentioned Spanish rent control should have a dampening effect on the amount it will benefit the landlord. Also, if I remember correctly this proposal was going to be given in the form of a tax relief. To receive it you have to make a tax declaration called Renta which would be reimbursed to you at the end of the year. It will not be the same as if young people were automatically given a larger amount of disposable income, which the landlord could try and milk when negotiating a lease with new tenants.