Include bills payable, notes payable and miscellaneous accruals. Net working capital is the excess of current assets over current liabilities here. Current assets are those assets which are normally converted into cash within an accounting year; and current liabilities are usually paid within an accounting year.
What for is working capital required by firm very much depends on the nature of the business which the firm is conducting. If the firm has business which deals with public utility services, obviously the requirement will be low. It is primarily because the amount becomes available as soon as services are sold and also the services arranged by the firm and immediately sold, without much difficulty and complication. On the other hand trading concerns need heavy amounts because these require funds for carrying goods traded. Similarly many industrial units will also need heavy amounts for carrying on their business. Many manufacturing concerns will also need sufficiently heavy amounts, the of course depends on the nature of commodities which are being manufactured.