Management Accounting · Flexible budgets
Fixed vs Flexible Budgets in Management Accounting
Updated 11 October 2026 · Fact-checked
A fixed budget is set for one planned activity level and does not change. A flexible budget is recalculated for the actual activity level, using cost behaviour: variable costs move with activity, fixed costs stay the same. You flex the budget so actual costs are compared with a fair, like-for-like target.
Understand Fixed vs Flexible Budgets
A fixed budget is prepared for one level of activity, such as 10,000 units. It is used for planning, for example to set targets, decide resources and agree cash needs. It stays the same even if actual activity turns out different.
The problem appears at the control stage. Suppose you budgeted for 10,000 units but made 12,000. Actual variable costs will be higher than the fixed budget. Comparing the two shows an adverse variance, but the cost rise may simply be because you made more units. The comparison is not like for like.
A flexible budget fixes this. It is recalculated for the actual level of activity. You split each cost into variable, fixed and semi-variable parts. Variable costs are scaled up or down with activity. Fixed costs are left unchanged within the relevant range. Semi-variable costs are split into their fixed and variable elements first.
The flexed budget then shows what costs should have been at the actual output. The difference between the flexed budget and actual results is a meaningful variance for control. The difference between the original fixed budget and the flexed budget is the effect of the change in volume.
Use fixed budgets for planning and for stable activity, or where most costs are fixed. Use flexible budgets for control, and for planning when activity is uncertain.
Key formulas to remember
- Flexed variable cost
- Flexed variable cost = budgeted variable cost per unit × actual activity
- Use the budgeted rate per unit of activity, not the actual rate.
- Flexed fixed cost
- Flexed fixed cost = original budgeted fixed cost
- Unchanged within the relevant range of activity.
- Semi-variable cost
- Total cost = fixed element + (variable rate × activity)
- Split it first, then flex only the variable part.
- Variance for control
- Variance = actual result − flexed budget
- For costs, actual above flexed budget is adverse. For sales and profit, actual above flexed is favourable.
How to solve Fixed vs Flexible Budgets questions
Use this method for any question asking you to flex a budget or compare actual results with budget.
- 1Identify the budgeted activity level and the actual activity level.
- 2Classify each cost as variable, fixed or semi-variable. Split semi-variable costs into fixed and variable parts.
- 3Work out the budgeted variable cost per unit by dividing the budgeted cost by budgeted activity.
- 4Multiply each variable cost per unit by actual activity. Keep fixed costs at the original budget figure.
- 5Flex revenue too if sales volume changed, using the budgeted selling price per unit.
- 6Add up the flexed totals and compute the flexed profit.
- 7Compare actual with the flexed budget. Label each difference favourable or adverse.
Quickest way: Per-unit shortcut
When to use it: Use this in Section A questions that give one budget and ask for a flexed figure.
- Divide the budgeted variable cost by budgeted units to get the rate.
- Multiply the rate by actual units.
- Add fixed cost only if the question asks for a total.
- Check that your answer moves in the right direction: more units means higher variable cost.
Common mistakes in Fixed vs Flexible Budgets
Flexing fixed costs along with variable costs.
You scale the whole budget by the activity ratio to save time.
Fix: Only scale variable costs. Keep fixed costs at the original figure.
Comparing actual costs with the original fixed budget for control.
It is the budget you were given, so it feels like the obvious comparison.
Fix: Flex the budget to actual activity first, then compare.
Not splitting semi-variable costs.
The cost is listed as one figure, so it looks like a single cost.
Fix: Separate the fixed and variable parts, using the information given, then flex only the variable part.
Using actual cost per unit to flex.
Actual data is in front of you and looks more up to date.
Fix: Always flex at the budgeted cost per unit. Otherwise you hide the price and efficiency variances.
Labelling variances wrongly as favourable or adverse.
You treat higher figures as always bad or always good.
Fix: Costs above budget are adverse. Revenue or profit above budget is favourable.
Worked examples
Example 1
A fixed budget for 5,000 units shows variable costs of $40,000 and fixed costs of $25,000. Actual output was 6,000 units. What is the flexed budget total cost?
Show the solution
- Variable cost per unit = $40,000 ÷ 5,000 = $8.
- Flexed variable cost = $8 × 6,000 = $48,000.
- Fixed cost stays at $25,000.
- Flexed total cost = $48,000 + $25,000 = $73,000.
Answer: $73,000
Example 2
A budget for 2,000 units shows sales of $100,000, variable costs of $60,000 and fixed costs of $20,000. Actual output and sales were 2,200 units, with sales of $108,000 and total costs of $86,000. Compare actual profit with the flexed budget profit.
Show the solution
- Selling price per unit = $100,000 ÷ 2,000 = $50. Flexed sales = $50 × 2,200 = $110,000.
- Variable cost per unit = $60,000 ÷ 2,000 = $30. Flexed variable cost = $30 × 2,200 = $66,000.
- Fixed cost stays at $20,000.
- Flexed profit = $110,000 − $66,000 − $20,000 = $24,000.
- Actual profit = $108,000 − $86,000 = $22,000.
- Actual profit is $2,000 below flexed profit, so the variance is $2,000 adverse.
Answer: Flexed budget profit is $24,000. Actual profit is $22,000, so the variance is $2,000 adverse.
Exam tips
- Read the question for the word 'flexed' or 'actual activity'. It tells you to scale variable costs.
- In multiple response questions, check each statement against the rule: fixed budgets do not change, flexible budgets adjust for activity.
- In number entry questions, show the per-unit rate on scrap paper first. It catches most arithmetic slips.
- Check the sign and label of every variance before you submit.
Practice questions from Flexible budgets
- Harlow Ltd's fixed budget for 10,000 units shows: direct materials $50,000, direct labour $30,000 (both fully variable), production overhead…
- Which statement about reporting variances using a flexed budget is correct?
- A company budgeted 8,000 units with a semi-variable cost of $46,000. At 12,000 units the semi-variable cost is expected to be $62,000. What …
- A company budgeted to produce 10,000 units with total costs of $85,000, of which $25,000 is fixed. Actual production was 12,000 units. What …
- A budget is flexed from 5,000 to 6,000 units. Which statement about the flexed budget is correct?
Fixed vs Flexible Budgets in other exams
The same ground in other exams, if you are preparing for more than one or want another angle on it.
Fixed vs Flexible Budgets: frequently asked questions
What is the main difference between a fixed and a flexible budget?
A fixed budget is set for one activity level and does not change. A flexible budget is adjusted to the actual activity level. This makes it better for comparing actual results with a fair target.
Why are flexible budgets used in management accounting?
They allow control by comparing like with like. Without flexing, a volume change can hide or create variances. A flexed budget isolates the cost differences that managers can actually influence.
Do fixed costs change in a flexible budget?
No, not within the relevant range of activity. Only variable costs change with activity. If activity moves outside the relevant range, fixed costs may step up or down, but the question will tell you.
Is a fixed budget ever better?
Yes. It suits planning, for setting targets and agreeing resources. It can also work where activity is stable or most costs are fixed, such as some service departments.