The amount of the Variable Deposit (if any) payable by a Clearing Member shall be determined as follows or on such basis as may be advised by CDP at any time and from time to time:—
V = (P×C) - B
Where V = Variable Deposit
P = Proportion
C = Total Clearing Fund Contribution
B = Base Deposit
Provided always that if the Variable Deposit is zero or less than zero, such Clearing ember shall not be required to contribute a Variable Deposit.