150.— Where, after interest has been paid in relation to a payable amount of local property tax, the payable amount is reduced—

(a) an appropriate adjustment shall be made of the amount of interest payable, and

(b) subject to section 960H of the Act of 1997 (as applied by section 120), a repayment shall be made of interest previously paid of such an amount as is necessary to secure that the total sum, if any, paid or payable in relation to local property tax is the same as it would have been if the amount by which the local property tax is reduced had never been due and payable.