variable expenses defined
variable expenses (and costs) vary in direct proportion to changes in output or activity in a responsibility center. variable expenses are activity based because they are incurred as a direct result of output, productive activity or work done. they would not exist were it not for the performance of some activity. a variable expense is necessarily zero at zero activity. variable expenses increase or decrease directly with changes in output; therefore, if output is doubled, the variable expense is doubled; or if output decreases by 10 percent, the expense decreases by 10 percent. the following list explains the primary characteristics a company should consider in establishing a practical definition of variable expenses