Upon the completion of any such improvement or works, the joint meeting of the governing bodies or boards of the contracting municipalities reorganized in accordance with the provisions of section 40:63-90 of this title, shall annually, before December first, make an estimate of and determine the probable cost and expense of the maintenance and operation thereof for the year beginning on the following January first, and shall cause the same to be certified by the secretary of the joint meeting to each of the contracting municipalities on or before December first in each year, and thereupon may from time to time, by resolution, duly adopted by the joint meeting, require the municipalities to pay to the treasurer of the joint meeting the whole or any part of their pro rata shares of such estimated amount for the year, in advance, and each municipality shall within thirty days after receiving such requisition pay to the treasurer of the joint meeting its pro rata share of the amount so required under such resolutions. If the amount so estimated and determined shall prove insufficient for the maintenance and operation of such public improvement or works for the year, the joint meeting may require the municipalities contracting for such public improvement to pay such additional amount as may be necessary for that purpose. This section shall not apply to municipalities which under the provisions of said section 40:63-90 are not required to reorganize the joint meeting upon the completion of the joint improvement or works.