If you take a deposit for a private tenancy on or after 1 April 2013 you will be legally obliged to protect this deposit in an authorised scheme. You can choose to protect the deposit in either a custodial or insurance based scheme and 3 separate companies have been appointed to provide this service in Northern Ireland.
Deposits taken before the 1 April 2013 do not need to be placed in a protection scheme, but should be kept in a separate account and clearly labelled with the name of the tenant. Keep clear records about when you received the deposit and provide your tenants with a receipt.