Any council member may, by writing filed with the municipal treasurer, direct that any portion of his annual compensation for serving in office be returned to the municipal treasury. For the purpose of this section, an executive or mayor who is also a member of the council under an existing plan shall be considered as a member of the council, and after the new plan goes into effect, his duties shall be only those of a member of council as prescribed by the new plan.
53 Pa.C.S. § 3162