Notwithstanding any provision of law to the contrary, all employers of members of retirement systems administered by the department shall transmit by a warrant or check to the department within fifteen days following the end of each calendar month the moneys due the department as determined by the statutes governing each system together with such reports as the department may require. The director may collect interest on any employer's overdue payments at the rate of one percent per month on the outstanding balance where necessary to secure adherence to timeliness requirements.