additional costs may include freight paid to acquire the goods, customs duties, sales or use taxes not recoverable paid on materials used, and fees paid for acquisition. for financial reporting purposes such period costs as purchasing department, warehouse, and other operating expenses are usually not treated as part of inventory or cost of goods sold. for u.s. income tax purposes, some of these period costs must be capitalized as part of inventory. costs of selling, packing, and shipping goods to customers are treated as operating expenses related to the sale. both international and u.s. accounting standards require that certain abnormal costs, such as those associated with idle capacity, must be treated as expenses rather than part of inventory.