The petty cash book is usually maintained on the basis of imprest system. Under it, a fixed amount, solely determined by the Head Cashier, is advanced to the Petty Cashier at the beginning of the period, may be, a week or a fortnight, or a month, by the Head Cashier. The petty cashier submits his accounts at the end of the period to the Head Cashier and the head cashier after examining the accounts gives him a fresh advance equivalent to the amount spent by him during the period. Thus, in the beginning of each period, the petty cashier has a fixed balance. The amount so advance to him is termed as “Imprest” or “Float”.