A flexible budget, also called a variable budget, is financial plan of estimated revenues and expenses based on the current actual amount of output. In other words, a flexible budget uses the revenues and expenses produced in the current production as a baseline and estimates how the revenues and expenses will change based on changes in the output. This is why it’s often called a variable budget. Management often uses flexible budgets before a period to predict both a best case and worse case scenario for the upcoming accounting period. This provides a "what if" look at the future of the company’s financial performance.
Flexible budgets can also be used after an accounting period to evaluate the successful areas and unsuccessful areas of the last period performance. Management carefully compares the budgeted numbers with the actual performance statistics to see where the company improved and where the company needs more improvement.