The resolution, ordinance, or vote, when adopted, shall be filed with the general treasurer of the state. Upon notification by the general treasurer that the provisions of this agreement have been approved by the secretary and are in full force and effect as of the effective date of participation of the city, town, or agency of the state, the appropriate officials thereof shall begin to withhold the contribution required from those employees for that coverage and to allocate from its corporate fund an amount equal to the amount of tax which would be imposed upon an employer by § 3111 of the federal Insurance Contributions Act, 26 U.S.C. § 3111, if the services for the political subdivision covered by the federal state agreement constituted employment within the meaning of the act. The contributions by the employees and the employer shall accrue beginning as of the effective date of participation of such city, town, or agency of the state as specified by the general treasurer. Unless otherwise specified in the resolution, ordinance, or vote and agreed to by the general treasurer and the secretary, the effective date of participation of any city, town, or agency of the state shall be the first day of the calendar year in which the ordinance, resolution, or vote shall be adopted.