Most businesses keep a small amount of petty cash to buy odd small items, such as stamps and so on and to receive the occasional small receipt such as reimbursement for a private phone call or photocopying. This is called the cash float or petty cash account.
Normally, there are more payments than receipts and therefore, the petty cash needs to be topped up with cash from the business bank account.
Under the imprest system, the amount of money in the petty cash is kept at a fixed sum or float (eg £100). Expense items are recorded on vouchers as they occur, so that at all times:
£ cash + £ vouchers = £ agreed float
When the petty cash is topped up, the amount of the top up should always be the total of the voucher payments since the last float.
The petty cash book looks much the same as the main cash book.