Cost Accounting · Budget and Budgetary Control

Flexible Budgets: How to Prepare Them with Solved Problems

Updated 10 October 2026 · Fact-checked

A flexible budget shows the expected costs and profit at several activity levels, not just one. To prepare it, split every cost into fixed, variable and semi-variable parts, keep fixed costs constant, multiply variable costs by the activity level, and add the total for each level.

Understand Flexible Budgets

A static budget is prepared for one level of activity. If actual output turns out different, comparing actual cost with that budget is unfair. A higher output will naturally cost more, and that does not mean poor control.

A flexible budget fixes this. It is a budget designed to change with the level of activity. It shows what costs should be at 60%, 80% or 100% capacity, so you can compare actual cost with the cost allowed for the actual output.

The idea rests on cost behaviour. Variable costs change in total with output but stay constant per unit. Fixed costs stay constant in total within the relevant range but change per unit. Semi-variable costs have a fixed part and a variable part, such as a telephone bill with a rental and a per-call charge. You must split these before you can flex them.

For control, you flex the original budget to the actual activity level. The difference between actual result and this flexed budget shows the real efficiency gap. The difference between the static budget and the flexed budget shows the effect of volume alone.

Flexible budgets are used mostly for overheads and for profit planning. They work only within a relevant range of activity. Outside that range, fixed costs may step up and the pattern breaks.

Key rules to remember

Flexed variable cost: Budgeted variable cost per unit × Actual (or budgeted level) units; Variable cost per unit stays constant. Total changes with activity.
Fixed cost in a flexible budget: Total fixed cost = same at every level (within relevant range); Do not scale fixed cost with output. Fixed cost per unit will change.
Variable rate of a semi-variable cost: (Cost at higher level − Cost at lower level) ÷ (Units at higher level − Units at lower level); This is the high-low method. Use it when two cost levels are given.
Fixed part of a semi-variable cost: Total cost at any level − (Variable rate × Units at that level); Check by testing the other given level.
Flexed budget cost: Fixed cost + (Variable cost per unit × Units); Use this for every cost line, including semi-variable costs after splitting.
Units at a capacity level: Units = Capacity % × Units at 100% capacity; Convert percentages to units before applying per-unit rates.
Profit at an activity level: Profit = Sales − (Flexed variable costs + Fixed costs); Sales scale with units at the selling price per unit.

How to solve Flexible Budgets questions

Use this method for any flexible budget question, whether it asks for overheads only or for full profit at several levels.

1Convert each activity level (such as 60%, 80%, 100%) into units or hours using the capacity given.
2Classify every cost line as fixed, variable or semi-variable. Read the wording and the data given at each level carefully.
3Split semi-variable costs into a variable rate and a fixed part. Use the high-low method if two levels are given. Show the working.
4Find the variable cost per unit for every variable item. If a cost is given as a total at one level, divide by the units at that level.
5Build a table with one column for each activity level. Put variable costs as per-unit rate × units, and repeat fixed costs unchanged.
6Total each column. Add sales and profit if asked, using selling price × units.
7If actual results are given, flex the budget to actual activity and compare line by line, marking each difference as favourable or adverse.
8Write one line of interpretation, such as which cost needs investigation.

Quickest way: Rate-and-fixed shortcut

When to use it: Use when time is short and the question gives cost at one level plus a note on behaviour, or two levels for semi-variable items.

Write each line as: variable rate per unit, and fixed amount. For example, 6 per unit + 60,000 fixed.
Fill the first column fully and check it against the given data.
For other columns, change only the units. Variable amounts move by rate × units, and fixed amounts are copied across.
Check one column total against any total given in the question before finishing.

Common mistakes in Flexible Budgets

Scaling fixed costs in proportion to activity.
Students apply the same percentage to every line without checking behaviour.
Fix: Mark each line F, V or SV first. Copy F lines across unchanged and apply the rate only to V lines.
Treating a semi-variable cost as fully variable or fully fixed.
The cost is given as a single total, so the split is easy to miss.
Fix: Always split it. With two levels, work out the rate using the high-low method and then find the fixed part.
Using percentages instead of units in the high-low method.
Activity is given as 50% and 80%, so students divide by 30.
Fix: Convert percentages to units first, then divide the cost change by the unit change.
Comparing actual cost with the static budget for control.
The static budget is the first figure given in the question.
Fix: Flex the budget to actual output and compare actual with that. Show the static-to-flexed change separately as the volume effect.
Computing variable cost per unit from a total at the wrong level.
A total is given at 80% but the student divides by 100% units.
Fix: Divide each total by the units at its own level before applying it to others.
Showing only totals with no layout or interpretation.
Students rush to the final number.
Fix: Present a columnar statement with clear headings, show the semi-variable split as working, and add a one-line comment.

Worked examples

Example 1

A factory has a capacity of 10,000 units at 100% activity. Per-unit costs are: direct materials ₹10, direct labour ₹6, variable overhead ₹4. Fixed overhead is ₹2,00,000. A semi-variable expense is ₹90,000 at 50% activity and ₹1,08,000 at 80% activity. The selling price is ₹80 per unit. Prepare a flexible budget at 60%, 80% and 100% activity, showing profit.

Show the solution

Units: 60% = 6,000; 80% = 8,000; 100% = 10,000. The semi-variable data are at 5,000 units and 8,000 units.
Split the semi-variable cost: variable rate = (1,08,000 − 90,000) ÷ (8,000 − 5,000) = 18,000 ÷ 3,000 = ₹6 per unit.
Fixed part = 90,000 − (6 × 5,000) = 90,000 − 30,000 = ₹60,000. Check at 8,000 units: 48,000 + 60,000 = 1,08,000, which agrees.
Direct materials at ₹10: 60,000; 80,000; 1,00,000. Direct labour at ₹6: 36,000; 48,000; 60,000. Variable overhead at ₹4: 24,000; 32,000; 40,000.
Semi-variable expense (₹6 per unit + ₹60,000): 96,000; 1,08,000; 1,20,000. Fixed overhead: 2,00,000 at each level.
Total cost: 60% = 60,000 + 36,000 + 24,000 + 96,000 + 2,00,000 = 4,16,000. 80% = 80,000 + 48,000 + 32,000 + 1,08,000 + 2,00,000 = 4,68,000. 100% = 1,00,000 + 60,000 + 40,000 + 1,20,000 + 2,00,000 = 5,20,000.
Sales at ₹80: 4,80,000; 6,40,000; 8,00,000.
Profit = Sales − Total cost: 4,80,000 − 4,16,000 = 64,000; 6,40,000 − 4,68,000 = 1,72,000; 8,00,000 − 5,20,000 = 2,80,000.

Answer: Total cost is ₹4,16,000, ₹4,68,000 and ₹5,20,000 at 60%, 80% and 100% activity. Profit is ₹64,000, ₹1,72,000 and ₹2,80,000 respectively.

Example 2

Static budget for 10,000 units: sales ₹10,00,000, variable costs ₹6,00,000, fixed costs ₹2,00,000. Actual output was 8,000 units with sales ₹8,10,000, variable costs ₹5,00,000 and fixed costs ₹2,10,000. Prepare a flexed budget at actual activity, compare it with actual results, and comment.

Show the solution

Static budget profit = 10,00,000 − 6,00,000 − 2,00,000 = ₹2,00,000. Selling price = ₹100 per unit and variable cost = ₹60 per unit.
Flex to 8,000 units: sales = 8,000 × 100 = 8,00,000. Variable cost = 8,000 × 60 = 4,80,000. Fixed cost stays at 2,00,000. Flexed profit = 8,00,000 − 4,80,000 − 2,00,000 = ₹1,20,000.
Actual profit = 8,10,000 − 5,00,000 − 2,10,000 = ₹1,00,000.
Compare actual with flexed: sales 8,10,000 − 8,00,000 = ₹10,000 favourable. Variable cost 5,00,000 − 4,80,000 = ₹20,000 adverse. Fixed cost 2,10,000 − 2,00,000 = ₹10,000 adverse.
Profit difference = 10,000 − 20,000 − 10,000 = ₹20,000 adverse (1,20,000 − 1,00,000).
Volume effect: static profit 2,00,000 to flexed profit 1,20,000 = ₹80,000 adverse, caused only by lower output.
Total difference from static budget = 80,000 + 20,000 = ₹1,00,000 adverse (2,00,000 − 1,00,000).

Answer: Flexed profit is ₹1,20,000 against actual ₹1,00,000, an adverse difference of ₹20,000. Of the ₹1,00,000 shortfall against the static budget, ₹80,000 is due to lower volume and ₹20,000 to cost and price performance. Variable cost overspend of ₹20,000 and fixed cost overspend of ₹10,000 need investigation, partly offset by ₹10,000 favourable sales.

Exam tips

Draw the columnar statement first, with headings like 60%, 80%, 100%. Marks are given for layout and for each correct line.
Show the semi-variable split as a separate working. Even if the final total is wrong, you still earn step marks.
In MCQs, check whether the question asks for total cost or cost per unit at a new level. Fixed cost per unit falls as activity rises, so the per-unit answer differs from the total.
When actual output is given, always flex before comparing. Writing 'flexed budget for actual output' earns marks for method.
Add a short comment, such as which cost lines need investigation or that the volume effect is outside management's control.

Practice questions from Budget and Budgetary Control

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.

Flexible Budgets: frequently asked questions

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

A static budget is prepared for one fixed activity level and does not change when actual output differs. A flexible budget is prepared for several activity levels, or adjusted to actual activity. It gives a fair basis for cost control because it allows for the cost that should arise at the actual output.

How do I split a semi-variable cost in a flexible budget problem?

Use the high-low method. Divide the change in cost by the change in units to get the variable rate per unit. Then subtract the variable part from the total at either level to get the fixed part. Always use units, not percentages, in the division.

Do fixed costs change in a flexible budget?

Fixed costs stay the same in total across activity levels within the relevant range. Only the fixed cost per unit changes. If the question says fixed cost rises at a certain level, such as a new supervisor above 90% activity, show that step as given.

Is a flexible budget used only for overheads?

No. It is used most often for overheads, but it can also cover materials, labour, sales and profit. Exam questions may ask for a full flexed statement showing sales, costs and profit at different capacity levels.