Section 18C. (a) In this section, ''budgeted aid'' shall mean unrestricted aid to cities and towns, including proceeds from the state lottery established under chapter 10, payments in lieu of taxes from the commonwealth to cities and towns and education aid to cities and towns under chapter 70.

(b) The state treasurer shall, subject to appropriation but not subject to allotment under section 9B of chapter 29, distribute budgeted aid to cities and towns. The distribution shall be made in 12 equal payments, on or before the last day of each month.

Notwithstanding clause Forty-first of section 7 of chapter 4 or any other general or special law to the contrary, the commissioner of revenue or any official responsible for a local reimbursement or assistance program reported by said commissioner under section 25A shall use, as appropriate, the most recent city and town population estimates of the United States Bureau of the Census in calculating distributions or assessments under local reimbursement or assistance programs. Such distribution programs shall include, but not be limited to, the chapter 70 school aid program, and aid to regional public libraries. Such assessments shall include, but not be limited to, air pollution control districts, the metropolitan area planning council, the old colony planning council, the Massachusetts Bay Transportation Authority and any other entity for which said commissioner is required to give notice under said section 25A.

(c) This section shall not be construed to prohibit the distribution of other state government payments to cities and towns that are not budgeted aid through 1 or more of the monthly payments to cities and towns. Nor shall this section be construed to prohibit the deduction from distributions to satisfy amounts owed to the state by cities and towns under section 20A or any other general or special law.