Councilmembers shall receive monthly pay for attendance at regular meetings as determined by Council, and shall be reimbursed for actual and necessary expenses incurred in the performance of duties. No ordinance increasing such compensation shall become effective until the first day of July following the next regular election, provided that such election follows the adoption of such ordinance by at least six months. The compensation of the Mayor or of any member of Council shall not be diminished during an active term of office.