According to general law, in the absence of a tenancy agreement, the tenant would pay rent in arrears. If there is a tenancy agreement, the landlord may require rent to be paid in advance. For example, at the start of a tenancy on 1st of May, the tenant may pay rent for the 4 weeks ahead and the rent would be due again on 1st of June. Basically, the rent is paid ahead of time, for a service yet to be received, unlike rent paid in arrears which is for a service already received. Rent payable in advance usually helps cut down on tenants owing.