TFC remains constant at all levels of output. These are ‘unavoidable’ costs’ and often referred to as overhead costs. In our example these were capital costs. Other fixed costs might include the rental a firm pay on its premises, the repayment costs of a loan, or money paid to a security firm to guard the premises. TFC is illustrated in Figure 5.5 as a horizontal line. The distance OF represents the value of fixed cost were to rise, for example due to increase in the price of capital, the curve would shift upwards, and vice versa.