What it means
Traditional budgeting starts with last year's numbers and adds an increment. Activity-based budgeting asks a prior question: what will we actually do next year, and what does each unit of that work cost?
The answer replaces the habit of simply adding 3% to everything. The method borrows its logic from activity-based costing, which traces overhead to activities such as processing orders, handling complaints or setting up machines.
Each activity gets a cost per unit of its driver. The budget then multiplies forecast volume by that unit cost, so a sales plan that grows orders by 20% grows the order-processing budget by the same logic.
This structure exposes waste that line-item budgets hide. An activity whose output nobody uses becomes visible, because it sits in the budget with a name, a driver and a price.
Department heads also defend activity levels and unit costs rather than fighting for percentage increases, which moves the conversation from politics toward operations. The cost is complexity.
Mapping activities, choosing drivers and maintaining unit costs takes real effort, so activity-based budgeting earns its keep mainly in organisations with heavy, varied overhead. The best drivers are countable, already measured and clearly linked to the work, and seasonality belongs in the model from the start so that the December rush does not create false variances.
Public bodies use versions of the idea to link funding to workload, and universities, hospitals and agencies often budget teaching, care or services by activity volume. Expect resistance from managers whose empires shrink, because activity budgets make overstaffing visible as a number.
Running a pilot in one division for a year teaches more than a company-wide rollout designed by committee. For any manager, even a lightweight version pays off.
Listing your team's ten main activities with rough unit costs often reveals that a fifth of the effort goes to work nobody would fund if asked directly. The principle is to fund the work, not the department.
In practice
Real-world examples.
Example
A distribution company budgets its warehouse by activities: receiving lines, picks and shipments, each with a measured unit cost. When the sales plan grows picks by 20%, the warehouse budget grows by exactly the cost of those extra picks.
Example
A university moves its faculties to activity-based budgeting, funding teaching by student credit hours and research by grant activity. Cross-subsidies that were invisible for decades become numbers that can be discussed openly.
Example
A shared-services centre in a bank maps its activities and finds that report production consumes 15% of its cost. A survey shows that most reports go unread, and the next budget funds the activity at half its previous level.
Formula
Calculation
Activity budget = Forecast driver volume x Cost per driver unit, added up across all activities.
Worked example. A fictional distribution company forecasts three activities. Order processing: 50,000 orders x $4 = $200,000. Handling complaints: 2,000 complaints x $30 = $60,000. Machine set-ups: 400 set-ups x $150 = $60,000. Total activity budget = $200,000 + $60,000 + $60,000 = $320,000. If next year's sales plan raises orders to 60,000, order processing becomes 60,000 x $4 = $240,000 and the total rises to $360,000, a change that last year's line-item budget would not have explained.Case study
Seen in the real world.
This case study is fictional and illustrative. A finance lead at Meridian Freight, an invented logistics firm, replaces across-the-board budget growth with activity budgets for the twelve activities that carry most of the firm's overhead. The exercise prices every service line, from customs paperwork to claims handling, for the first time.
Two low-value activities turn out to cost far more than anyone assumed, and both are outsourced within a year. The board now reviews the budget each cycle as a priced menu of activities, and debates focus on which work should exist rather than whose department grows. Managers also learn to challenge their own requests, because every extra activity now arrives with a driver, a volume and a price that colleagues can question.
Watch out
Common mistakes.
- Building an activity model too detailed to maintain. Start with the dozen activities that carry most of the cost and refine only where decisions depend on it.
- Treating unit costs as fixed forever. Drivers and rates need an annual refresh, or the budget quietly becomes last year's numbers again.
- Using activity-based budgeting everywhere. Stable, small overhead centres are cheaper to budget by simple increments, so target the big, variable overhead.
Questions
People also ask.
How does ABB differ from zero-based budgeting?
Zero-based budgeting makes managers justify every line from scratch. ABB goes further by pricing named activities from their drivers, which gives the justification an operational unit.
Is ABB only for manufacturers?
No. Universities, hospitals and agencies use activity models widely, and any organisation with large shared overhead can benefit.
What data does it need?
A list of activities, a driver for each and a cost per driver unit. Time surveys and system logs usually supply the first pass, because most organisations already record the raw volumes.
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