Supplementary costs, also known as overhead costs, indirect costs, or fixed costs, are general expenses that are incurred for an undertaking as a whole and do not vary with changes in production levels. They include administration, interest, taxes, and maintenance costs. In contrast, variable costs, also known as direct costs or prime costs, are directly related to the production of goods or services. Fixed costs are time-related and do not change over a specific period of time, while variable costs can vary depending on the level of production. In short-term situations, supplementary costs are considered to be fixed, while in the long-term they may become variable.