A flexible budget, or “flex” budget itemizes different expense levels depending upon changes in the amount of actual revenue. In its simplest form, the flex budget will use percentages of revenue for certain expenses, rather than the usual fixed numbers. This allows for an infinite series of changes in budgeted expenses that are directly tied to revenue volume.
However, this approach ignores changes to other costs that do not change in accordance with small revenue variations. Consequently, a more sophisticated format will also incorporate changes to many additional expenses when certain larger revenue changes occur, thereby accounting for step costs. By making these changes to the budget, a company will have a tool for comparing actual to budgeted performance at many levels of activity.
Though the flex budget is a good tool, it can be difficult to formulate and administer. One problem with its formulation is that many costs are not fully variable, instead having a fixed cost component that must be included in the flex budget formula. Another issue is that a great deal of time can be spent developing step costs, which is more time than the typical accounting staff has available, especially when in the midst of creating the standard budget. Consequently, the flex budget tends to include only a small number of step costs, as well as variable costs whose fixed cost components are not fully recognized.