Working capital is the average amount of capital, in excess of net plant, that is necessary for
business operations (4). Examples include inventories, petty cash, prepayments, minimum bank
balances, and cash working capital. Cash working capital is the average amount of money that
investors supply to bridge the gap between the time that expenses are incurred and the time that
revenues are received. In some cases, customers pre-pay for services. This prepayment can be
shown as an offset to cash working capital. When investors have provided working capital, it
should be included in the rate base.