§ 61. Date for determining last completed assessment rolls. In computing the amount which may be raised by tax on real estate by a county, city, village or school district within the limitation prescribed by article eight of the constitution, the determinations as to the last completed assessment roll, as defined in subdivision seven-a of § 2.00 of the local finance law, shall be made on or before the date upon which the amount to be raised by tax on real estate by or for such county, city, village or school district is actually determined. For the purposes of this section an assessment roll shall mean such assessment roll as finally completed by the assessors or other officer or body authorized to prepare such roll.