(1) The revision of rent between the landlord and the tenant shall be in accordance with the terms of the tenancy agreement.
(2) Where, after the commencement of tenancy, the landlord has entered into an agreement in writing with the tenant prior to the commencement of the work and has incurred expenditure for carrying out improvement, addition or structural alteration in the premises occupied by the tenant, which does not include repairs necessary to be carried out under section 15, the landlord may increase the rent of the premises by an amount as agreed to between the landlord and the tenant, and such increase in rent shall become effective from one month after the completion of such work.