(2)  The competent authority may in the first instance estimate the amount of development charge payable in respect of any proposed development of land and issue an interim order requiring the payment of such estimated amount.

(3)  The competent authority shall serve a copy of the interim order on the person liable for the payment of the development charge in accordance with section 37.

(4)  Where an interim order is issued under subsection (2) in respect of any proposed development of land, the competent authority shall, within 12 months from the date of the grant of the planning permission or conservation permission for that proposed development, determine the actual amount of development charge payable and make a final order.

(5)  If no final order is made at the end of the period allowed under subsection (4), the estimated amount shall be deemed to be the actual amount of development charge payable in respect of the proposed development and the interim order shall be deemed to be a final order.

(6)  Any additional development charge payable under a final order issued under subsection (4) shall be paid within such time as the competent authority may specify in the final order.

(7)  Where a final order issued under subsection (4) is for an amount lower than the amount in the interim order relating to the same proposed development, the competent authority shall refund the excess without interest to the person who paid the estimated amount under the interim order.