129M.— (1) On receiving a copy of the budget adopted by a BID company under section 129J(3) or 129L(3), the rating authority concerned shall determine the annual BID multiplier to be levied against the valuation of each rateable property in the business improvement district to which the budget relates.

(2) The annual BID multiplier is to be determined by the formula

A + B

C

where

A is the annual BID contribution determined by the BID company pursuant to section 129L(2),

B is the total of—

(a) all estimated costs that the rating authority expects to incur over the next chargeable period in performing functions related to the BID scheme, and

(b) if the budget is for the first chargeable period of the scheme under section 129J, all costs incurred by the rating authority in relation to the BID proposal on which the scheme is based, and

C is the aggregate valuation of all rateable property situate in the relevant business improvement district according to the latest valuation list in force at the time of determining the annual BID multiplier under this section.]