Expenses on an income statement are considered product or period costs. Product costs
are those costs assigned to an inventory account that eventually become part of cost of goods sold. Examples of manufacturing product costs are raw materials used, direct labor, factory supervisor's salary, and factory utilities. In a manufacturing company, product costs are also called manufacturing costs
. In a service company, product costs are also accumulated as inventory (such as the cost of an audit or of a will). Period costs
are those costs recorded as an expense in the period they are incurred. Selling expenses such as sales salaries, sales commissions, and delivery expense, and general and administrative expenses such as office salaries, and depreciation on office equipment, are all considered period costs. In a manufacturing company, these costs are often referred to as nonmanufacturing costs
. There are three categories of manufacturing costs: direct materials, direct labor, and overhead.
are those materials (including purchased parts) that are used to make a product and can be directly associated with the product. Some materials used in making a product have a minimal cost, such as screws, nails, and glue, or do not become part of the final product, such as lubricants for machines and tape used when painting. Such materials are called indirect materials
and are accounted for as manufacturing overhead. Direct labor
is the cost of the workers who make the product. The cost of supervisory personnel, management, and factory maintenance workers, although they are needed to operate the factory, are classified as indirect labor
because these workers do not use the direct materials to build the product. Manufacturing overhead
costs include indirect materials, indirect labor, and all other manufacturing costs. Depreciation on factory equipment, factory rent, factory insurance, factory property taxes, and factory utilities are all examples of manufacturing overhead costs. Together, the direct materials, direct labor, and manufacturing overhead are referred to as manufacturing costs
. The costs of selling the product are operating expenses (period cost) and not part of manufacturing overhead costs because they are not incurred to make a product.