The Lessor shall be responsible to pay only the portion of the Premises and Property Tax which is calculated from the base of rental under Clause 5 the present applicable rate enforceable at the time of this Agreement. Should the assessment of the authority be higher than the actual rental base under Clause 5 and/or should the current rate of Premises and Property Tax be changed to the rate higher than the present applicable rate enforceable at the time of this Agreement, the Tenant then shall pay to the Lessor an additional sum equal to the amount increasingly imposed on the Lessor. Such payment shall be made to the Lessor within three (3) days upon receipt of notice from the Lessor. If the Lessor has necessarily prepaid such tax due to payment delay of the Tenant, the Tenant shall immediately reimburse the Lessor for such tax together with a fine at the rate of seven point five (7.5) per cent per annum of such tax.