Performance Management · Activity-based costing

Cost Drivers and Cost Pools in Activity-Based Costing

Updated 11 October 2026 · Fact-checked

In activity-based costing, a **cost pool** collects the overhead costs of one activity. A **cost driver** is the factor that causes that activity's cost to rise or fall. You divide each pool's cost by its total driver volume to get a cost per driver unit, then charge products by their use of the driver.

Understand Cost Drivers and Cost Pools in ABC

Traditional absorption costing spreads all overhead using one base, usually labour hours or machine hours. That can distort product costs when overheads are not caused by those hours. ABC fixes this by tracing overhead to the activities that cause it.

An activity is a task the business performs that uses resources, such as setting up machines, inspecting output, handling materials or processing orders. First you identify the main activities. Then you group the overhead costs linked to each activity into a cost pool. A pool is simply the total overhead cost of that activity (or of a set of activities that share the same driver).

A cost driver is the measure of what causes the cost of an activity. If setting up machines costs more when there are more batches, the number of set-ups is the driver. If inspection costs rise with the number of inspections, that is the driver. The driver must have a clear cause-and-effect link to the cost. It should also be measurable and the data should be available at a reasonable cost.

The two linked ideas are: pools say how much cost, drivers say why and how to share it. Products that use more of the driver absorb more of the pool. Low-volume, complex products often end up with higher unit costs than under traditional methods.

A common classification in ABC is the cost hierarchy: unit-level activities (done for every unit, such as machining), batch-level (done per batch, such as set-ups), product-level (supporting a product, such as design) and facility-level (sustaining the site, such as rent). Facility-level costs are hard to link to a driver and are often absorbed on a simple basis.

Key rules to remember

Cost per unit of cost driver: Cost per driver unit = Total cost in the pool ÷ Total volume of the cost driver; Use the total driver volume for all products in the period, not for one product.
Overhead absorbed by a product: Overhead charged to product = Cost per driver unit × Driver units used by the product; Repeat for every pool and add the results. Divide by units produced for a unit cost.
Choosing a driver (rule): Good driver = causal link to cost + measurable + data available at reasonable cost; If two drivers fit, choose the one with the stronger cause-and-effect link.
Cost hierarchy: Unit-level → Batch-level → Product-level → Facility-level; Match the driver to the level: units, batches, products or no real driver.

How to solve Cost Drivers and Cost Pools in ABC questions

Use this order for any question on pools and drivers. It keeps the numbers tidy and shows the marker your logic.

1List the activities named in the question and the overhead cost given for each.
2Group costs into cost pools. Combine activities only if they share the same driver.
3For each pool, pick the driver that causes the cost. Check it has a causal link and that data exists.
4Find the total driver volume for the period across all products.
5Calculate the cost per driver unit: pool cost ÷ total driver volume.
6Multiply by each product's driver usage to get the overhead charged to it.
7Add the pools for each product, then divide by units made if a unit cost is needed.
8Check that the total overhead absorbed equals the total overhead in the pools.

Quickest way: Pool, driver, rate, charge

When to use it: Use this for Section A and OT case questions where you need one rate or one product's overhead quickly.

Underline the pool cost and the matching driver in the question.
Take the total driver volume across all products, not just the product asked about.
Divide to get the rate, then multiply by the product's usage.
For driver choice questions, pick the option that causes the cost, such as batches for set-up costs, not the one that is simply convenient.
Do a total check: the sum charged to all products should equal the pool.

Common mistakes in Cost Drivers and Cost Pools in ABC

Dividing the pool cost by the driver volume of one product only.
You focus on the product named in the question and forget the rate must be shared across all products.
Fix: Always add the driver volumes for every product first. Then calculate one rate for the pool.
Choosing a volume-based driver, such as machine hours, for every pool.
It copies the traditional absorption habit and avoids thinking about causes.
Fix: Ask what makes this cost go up. Set-ups follow batches, orders follow number of orders, inspections follow inspections.
Mixing units, such as using cost per batch against units produced.
Data tables show batches and units side by side and it is easy to grab the wrong line.
Fix: Write the driver unit next to the rate, for example ₹ per set-up, and multiply only by that same unit.
Grouping activities with different drivers into one pool.
You try to save time by reducing the number of pools.
Fix: Pool costs only when they are driven by the same factor. Otherwise keep separate pools.
Trying to force a driver on facility-level costs.
You assume ABC must trace every cost.
Fix: State that facility-level costs have no clear driver and are usually absorbed on a simple basis or treated separately.
Giving a driver without explaining why in a written answer.
You treat it as a naming exercise.
Fix: Add a short reason: the driver causes the cost, can be measured and the data is available.

Worked examples

Example 1

A company makes products X and Y. Overheads for the period: set-up costs ₹3,60,000 and inspection costs ₹1,80,000. X needs 40 set-ups and 60 inspections. Y needs 80 set-ups and 120 inspections. Using set-ups and inspections as the drivers, find the overhead charged to each product.

Show the solution

Set-up pool: ₹3,60,000. Driver is the number of set-ups. Total set-ups = 40 + 80 = 120.
Set-up rate = ₹3,60,000 ÷ 120 = ₹3,000 per set-up.
Inspection pool: ₹1,80,000. Total inspections = 60 + 120 = 180.
Inspection rate = ₹1,80,000 ÷ 180 = ₹1,000 per inspection.
Product X: set-ups 40 × ₹3,000 = ₹1,20,000. Inspections 60 × ₹1,000 = ₹60,000. Total = ₹1,80,000.
Product Y: set-ups 80 × ₹3,000 = ₹2,40,000. Inspections 120 × ₹1,000 = ₹1,20,000. Total = ₹3,60,000.
Check: ₹1,80,000 + ₹3,60,000 = ₹5,40,000, which equals ₹3,60,000 + ₹1,80,000.

Answer: Product X is charged ₹1,80,000 and product Y is charged ₹3,60,000 of overhead.

Example 2

A hospital laundry has these overhead costs: collection and delivery ₹2,40,000; washing and drying ₹6,00,000. Cost drivers: number of collections (800) for the first pool and kilograms washed (1,00,000 kg) for the second. A ward uses 50 collections and 4,000 kg. Suggest why these drivers are suitable and find the overhead charged to the ward.

Show the solution

Collection cost rises with the number of trips made, so collections have a clear causal link. Washing cost rises with the weight processed, so kilograms is a sensible driver. Both are easy to record.
Collection rate = ₹2,40,000 ÷ 800 = ₹300 per collection.
Washing rate = ₹6,00,000 ÷ 1,00,000 = ₹6 per kg.
Ward collection charge = 50 × ₹300 = ₹15,000.
Ward washing charge = 4,000 × ₹6 = ₹24,000.
Total charge = ₹15,000 + ₹24,000 = ₹39,000.

Answer: The ward is charged ₹39,000: ₹15,000 for collections and ₹24,000 for washing.

Exam tips

In OT questions, match the driver to the cost cause. Set-ups link to batches, purchasing to orders and quality checks to inspections.
Always compute the rate from total driver volume across all products, then apply it to the product asked about.
In Section C, set out one pool per row in a small calculation: pool cost, driver volume, rate, then product charge. This earns method marks even if you slip.
For written parts, justify a driver with three points: causal link, measurable and data available at reasonable cost.
Remember OT marking is all or nothing, so check units and the driver volume before you choose your answer.

Practice questions from Activity-based costing

Cost Drivers and Cost Pools in ABC in other exams

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

Cost Drivers and Cost Pools in ABC: frequently asked questions

What is a cost driver in activity-based costing?

A cost driver is the factor that causes the cost of an activity to change, such as the number of set-ups or orders. It is used to share a cost pool among products. A good driver has a clear cause-and-effect link and can be measured.

What is a cost pool in ABC?

A cost pool is the total overhead cost gathered for one activity, or for activities that share the same driver. You divide it by the driver volume to get a rate. Each product is then charged for the driver units it uses.

How do I choose a cost driver in an ACCA PM question?

Ask what makes the cost increase. Choose the driver with the strongest causal link, such as batches for set-up costs. Check that the data can be measured at a sensible cost. Use the information the question gives you.

Can I combine several activities into one cost pool?

Yes, if they are all driven by the same factor. If they have different drivers, keep separate pools. Combining unlike activities makes the rate less accurate.