Deposits | Housing
Generally, you will pay a deposit before moving in to a property. This remains your money and should be returned to you in full once you leave unless your landlord has a good reason to make deductions to cover costs such as for damage to the property or if you have not been paying your agreed rent.
Your deposit must be held in an authorised scheme if you are an assured shorthold tenant and, from 1 June 2019, the maximum tenancy deposit is equal to 5 weeks' rent.
Shelter provide good resources on deposits, available here