Constructing a budget
Constructing a Budget
This topic is assessed in IBDP Business Management at Higher Level (HL) only.
A budget is a quantified financial plan expressed in monetary terms, covering a defined future period — typically one month, one quarter, or one year. It sets out the expected income and expenditure of a business or one of its cost or profit centres, providing the financial targets against which actual performance is later compared. Budgeting is one of the most widely used tools in management accounting because it forces forward planning, creates accountability, and enables the early identification of financial problems through variance analysis.
Types of budget
The two primary budget types in the IB specification are:
Income budget (revenue budget): sets out the expected revenue for the period, broken down by product line, territory, or customer type. It provides the financial target for sales and marketing activity. An income budget is only as reliable as the sales forecast on which it is based — overoptimistic revenue budgets are one of the most common sources of budget variance.
Expenditure budget (cost budget): sets out the planned expenditure for the period, covering fixed costs (rent, insurance, management salaries), variable costs (materials, direct labour), and semi-variable costs. Expenditure budgets apply to all cost centres as well as to the cost side of profit centre budgets. They are constructed by estimating the volume of activity expected and the unit cost of each resource required to deliver it.
Together, the income and expenditure budgets produce a profit budget (or budgeted profit and loss account) — the expected profit or loss for the period if both income and expenditure targets are met.
How budgets are set
Budgets can be set using several approaches:
- Incremental budgeting: the most common approach in practice — last year's actual figures are used as a starting point, and adjustments are made for expected changes (inflation, volume changes, new activities). Simple and fast, but perpetuates inefficiencies if last year's spending was itself excessive.
- Zero-based budgeting (ZBB): every line of expenditure must be justified from scratch each period — no assumption is made that previous spending should continue. More rigorous and effective at eliminating wasteful spending, but very time-consuming and resource-intensive to implement.
- Top-down budgeting: senior management set the overall budget targets and allocate them to departments. Fast and ensures corporate priorities are reflected, but may lack the operational insight of managers closer to the activity.
- Bottom-up budgeting: individual departments or profit centres prepare their own budget proposals, which are consolidated and approved by senior management. More time-consuming but typically generates more realistic and accepted budgets because the people responsible for delivery have ownership of the targets.
Constructing an expenditure budget
A basic expenditure budget is constructed by listing each category of cost, estimating the quantity or usage, and applying the relevant unit cost. The total of all cost lines gives the total budgeted expenditure for the period. Where costs are variable, the budget must be linked to the volume assumption used in the income budget — if sales volume changes, variable cost budgets must be recalculated accordingly.
The manager of Outlet 7 is preparing the budget for the first quarter (January–March). The outlet expects to serve 14,200 customers at an average spend of £8.40.
Income budget:
\[ \text{Budgeted revenue} = 14{,}200 \times £8.40 = £119{,}280 \]Expenditure budget:
| Cost category | Basis | Budgeted amount (£) |
|---|---|---|
| Ingredients and packaging (variable) | £3.20 per customer × 14,200 | 45,440 |
| Staff wages (semi-variable) | Fixed £22,000 + £0.40 variable per customer | 27,680 |
| Rent and rates (fixed) | Fixed per quarter | 14,400 |
| Utilities (semi-variable) | Base £2,800 + £0.15 per customer | 4,930 |
| Allocated head office overhead | Apportioned fixed amount | 6,200 |
| Total budgeted expenditure | 98,650 |
Budgeted profit contribution (before full head office overhead):
\[ \text{Budgeted profit} = £119{,}280 - £98{,}650 = £20{,}630 \]This budget sets clear, quantified targets for Outlet 7's manager. If actual revenue falls short of £119,280 or actual costs exceed £98,650, a variance will be recorded — triggering investigation and a management response (explored in B2027).
The importance of realistic assumptions
A budget is only useful if it is based on realistic assumptions. An income budget built on an overoptimistic sales forecast creates targets that are unlikely to be met, producing adverse variances that demoralise managers and obscure genuine performance problems. An expenditure budget that underestimates costs creates an illusion of efficiency that collapses when actual costs are recorded. The quality of the budgeting process depends critically on the quality of the forecasting and cost estimation that underpins it.
Key Takeaways
- A budget is a quantified financial plan setting out expected income and expenditure for a defined future period.
- Income budgets set revenue targets; expenditure budgets set cost targets; together they produce a budgeted profit figure.
- Budget setting approaches include incremental (prior year + adjustments), zero-based (justify all from scratch), top-down (senior management set targets), and bottom-up (departments propose targets).
- Variable cost budgets must be linked to the volume assumptions in the income budget — if expected volume changes, variable cost budgets must be recalculated.
- Budget quality depends entirely on the quality of the underlying assumptions — overoptimistic revenue or underestimated costs produce budgets that create misleading variance signals.