The expense incurred in the provision of supplemental services within a district shall be financed in accordance with the district plan upon which the establishment or extension of the district was based, provided that the cost of supplemental services shall not include the cost to the district of services performed by the municipality on a city-wide basis. Any property tax charges or business license fee and occupation tax surcharges shall be levied and collected in the same manner, at the same time, and by the same officers as other city taxes and assessments.