Wherever used in this section, the phrase “recurring expenditure” means an expenditure for a purpose for which an appropriation was made in each of the three preceding fiscal years. If any expenditure, other than a recurring expenditure, authorized in the budget or by the town meeting is of so large an amount that the tax laid to pay it would make the total tax so high as, in the judgment of the board, to be inconsistent with the public welfare, the board may apportion the tax for such expenditure over a period of not more than five years, and the amount apportioned each year shall be thereafter included in the budget as a fixed charge until such time as the total amount of such expenditure has been paid. If the electors of such town, at a legal meeting held for such purpose, vote to issue bonds, the interest on such bonds and an annual appropriation for a sinking fund sufficient to pay the same at maturity shall be included in the budget as a fixed charge. The provisions of this section shall not apply to any expenditure which is to be met by the proceeds of a bond issue and which has been authorized by vote of any town at any meeting thereof. Any charter provision of any municipality authorizing the apportionment of the tax laid for any recurring expenditure over a period of years is repealed. The provisions of this section shall apply to any town having a board of finance created by special act and shall become a part of such special act upon the adoption of the provisions of this section by a town at any annual or special meeting of the electors of such town called for that purpose.