BID levy is to be imposed in a business improvement district only for periods ("chargeable periods") falling within the period in which BID arrangements are in force in respect of the district.
The length of any chargeable period, and the day on which it begins, are to be such as may be specified in the BID arrangements.
The amount of BID levy for any chargeable period—
is to be calculated in such manner as may be provided in the BID arrangements, and
may be different for different cases.