If at the time of a remittance of mixed beverage tax receipts by the comptroller under § 183.051, Tax Code, the amount collected by the comptroller from permittees in a municipality that has pledged a portion of its mixed beverage tax receipts under § 1504.256 is less than the total amount required to be collected from those permittees by Chapter 183, Tax Code, then the amount to be pledged under § 1504.256 is an amount equal to the total amount actually collected from permittees in the municipality multiplied by a fraction, the numerator of which is the amount of mixed beverage tax receipts pledged under § 1504.256 for the quarterly period and the denominator of which is the total amount required to be collected from permittees in the municipality during that period.