Management Accounting · Flexible budgets

How to Prepare a Flexible Budget Step by Step

Updated 11 October 2026 · Fact-checked

A flexible budget restates the original budget at the actual activity level. You work out the variable cost per unit, multiply it by actual activity, keep fixed costs unchanged, and split semi-variable costs into fixed and variable parts. You then compare the flexed budget with actual results to find fair variances.

Understand Preparing a Flexible Budget

A fixed budget is set for one planned level of activity. If actual activity differs, comparing actual costs with that budget is unfair. Higher output will naturally cost more, so the variance tells you little about control.

A flexible budget fixes this. You change the budget to what costs should have been at the actual activity level. Then you compare like with like. The difference between flexed budget and actual is a useful measure of cost control.

The method depends on cost behaviour. Variable costs change in total with activity, so you flex them. Fixed costs stay the same in total within the relevant range, so you do not flex them. Semi-variable costs have both parts. You split them first, then flex only the variable part.

Activity can be units produced, units sold, labour hours or machine hours. Use the measure that drives the cost. In most MA questions it is units.

Note that the flexed budget is built from the original budget's cost rates, not from actual costs. Actual results are only used at the end, for comparison.

Key formulas to remember

Variable cost per unit: Variable cost per unit = Budgeted variable cost ÷ Budgeted activity; Find this from the original budget before you flex.
Flexed variable cost: Flexed variable cost = Variable cost per unit × Actual activity; Use actual activity, not budgeted activity.
Flexed fixed cost: Flexed fixed cost = Original budgeted fixed cost; Fixed costs do not change within the relevant range of activity.
Semi-variable cost: Total cost = Fixed element + (Variable rate × Activity); Split the cost first, often with the high-low method, then flex the variable part only.
Flexed budget variance: Variance = Flexed budget − Actual cost (or the reverse for income); Costs: actual below flexed budget is favourable. Income: actual above flexed budget is favourable.

How to solve Preparing a Flexible Budget questions

Use this method for any question asking you to flex a budget or compare actual results with a flexed budget.

1Read the question and note the budgeted activity level and the actual activity level.
2Classify each cost line as variable, fixed or semi-variable. Look for clues in the wording.
3Work out the budgeted rate per unit for each variable cost and for sales revenue. Divide the budget figure by budgeted activity.
4Split any semi-variable cost into its fixed and variable elements, for example with the high-low method.
5Multiply each variable rate by actual activity. Copy fixed costs across unchanged. Add fixed and variable parts for semi-variable costs.
6Total the flexed budget and work out flexed profit if required.
7Compare each flexed figure with actual and label each variance favourable or adverse.
8Check that the final answer is the figure the question asks for, such as a single cost line or total profit.

Quickest way: Rate times actual units, fixed costs copied

When to use it: Use this in Section A objective questions where you need one flexed figure and have little time.

Identify the single cost line you need and its behaviour.
If variable, calculate budget ÷ budgeted units × actual units.
If fixed, write down the original budget figure and stop.
If semi-variable, use fixed part + variable rate × actual units.
Check the answer against the budget. If activity rose, a variable cost should rise too.

Common mistakes in Preparing a Flexible Budget

Flexing fixed costs along with variable costs.
Students apply one ratio to the whole budget to save time.
Fix: Classify every line first. Only variable parts move with activity.
Using actual cost figures to calculate the rate per unit.
Actual and budget figures sit side by side and get mixed up.
Fix: Always calculate the rate from the original budget and then multiply by actual activity.
Treating a semi-variable cost as fully variable or fully fixed.
The split is not always shown clearly.
Fix: Separate fixed and variable elements, then flex only the variable element.
Comparing actual results with the original budget instead of the flexed budget.
The original budget is the first one shown in the data.
Fix: If activity differs, always compare actual with the flexed budget to judge cost control.
Getting favourable and adverse the wrong way round.
Rules for costs and income are opposite.
Fix: For costs, actual lower than flexed is favourable. For sales, actual higher than flexed is favourable.

Worked examples

Example 1

A budget for 4,000 units shows direct materials $24,000, direct labour $36,000 (both variable) and fixed overheads $20,000. Actual output was 4,500 units. What is the flexed budget total cost?

Show the solution

Materials rate = $24,000 ÷ 4,000 = $6 per unit.
Labour rate = $36,000 ÷ 4,000 = $9 per unit.
Flexed materials = $6 × 4,500 = $27,000.
Flexed labour = $9 × 4,500 = $40,500.
Fixed overheads stay at $20,000.
Total = $27,000 + $40,500 + $20,000 = $87,500.

Answer: $87,500

Example 2

A budget for 2,000 units has sales of $50,000, variable costs of $22,000, a semi-variable cost of $9,000 and fixed costs of $14,000. The semi-variable cost has a fixed element of $5,000. Actual output and sales were 2,400 units. Actual profit was $19,500. Find the flexed budget profit and the profit variance against the flexed budget.

Show the solution

Sales rate = $50,000 ÷ 2,000 = $25 per unit. Flexed sales = $25 × 2,400 = $60,000.
Variable cost rate = $22,000 ÷ 2,000 = $11 per unit. Flexed = $11 × 2,400 = $26,400.
Semi-variable variable element = $9,000 − $5,000 = $4,000. Rate = $4,000 ÷ 2,000 = $2 per unit. Flexed variable part = $2 × 2,400 = $4,800.
Flexed semi-variable cost = $5,000 + $4,800 = $9,800.
Fixed costs stay at $14,000.
Flexed profit = $60,000 − $26,400 − $9,800 − $14,000 = $9,800.
Actual profit $19,500 is higher than flexed profit $9,800, so the variance is $19,500 − $9,800 = $9,700 favourable.

Answer: Flexed profit is $9,800 and the variance is $9,700 favourable.

Exam tips

Write the budgeted and actual activity levels at the top of your working before anything else.
In multiple response questions, check each statement for cost behaviour. Fixed costs staying the same is a common correct option.
For number entry, follow the rounding instruction exactly and enter only the number, with no units unless asked.
In Section B, show the rate per unit for each line. This helps you spot errors and keeps your working tidy.
Check the direction of the variance. Ask whether the result is better or worse for profit.

Practice questions from Flexible budgets

Preparing a Flexible Budget in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Preparing a Flexible Budget: frequently asked questions

What is the difference between a fixed budget and a flexible budget?

A fixed budget is set for one activity level and does not change. A flexible budget is restated at the actual activity level. This lets you compare like with like.

Do fixed costs change in a flexible budget?

No. Fixed costs stay at the original budgeted amount within the relevant range of activity. Only variable costs and the variable part of semi-variable costs change.

How do I flex a semi-variable cost?

Split it into a fixed element and a variable rate per unit. The question may give this or you may use the high-low method. Then total cost is the fixed element plus variable rate times actual activity.

Why do we flex the budget before calculating variances?

Without flexing, a change in activity distorts the variance. Flexing removes the effect of volume, so the remaining variance shows how well costs were controlled.