Management Accounting · Alternative cost accounting principles

Activity Based Costing (ABC) for ACCA Management Accounting

Updated 11 October 2026 · Fact-checked

Activity based costing (ABC) assigns overheads to products using the activities that cause those costs. You group overheads into cost pools, choose a cost driver for each pool, divide the pool by its driver volume to get a rate, then multiply that rate by each product's driver usage.

Understand Activity Based Costing (ABC)

Traditional absorption costing spreads overheads using one rate, usually per direct labour hour or machine hour. This works when products use overheads in proportion to volume. In many businesses they do not.

Activity based costing (ABC) starts from a different idea: products do not cause overheads directly. Activities cause overheads, and products consume activities. Setting up machines, inspecting output, processing orders and handling materials all cost money. A product that needs many set-ups should carry more set-up cost.

A cost pool is a collection of overhead costs linked to one activity, for example all machine set-up costs. A cost driver is the factor that causes the cost of that activity to change, for example the number of set-ups. You divide each cost pool by the total number of cost drivers to get a cost driver rate.

This matters most for low-volume, complex products. They need many set-ups, inspections and orders relative to their output. Volume-based absorption under-costs them and over-costs simple high-volume products. ABC corrects this and gives a more accurate product cost, which supports better pricing and product decisions.

ABC has limits. It takes time and money to identify activities and collect driver data. Some overheads, such as factory rent, have no clear driver and must still be shared arbitrarily. It also uses historical costs, so it is less useful if activities change quickly.

Key formulas to remember

Cost driver rate: Cost driver rate = Total cost of the activity pool ÷ Total volume of the cost driver; Calculate one rate per cost pool. Use the total driver volume across all products.
Overhead assigned to a product: Overhead assigned = Cost driver rate × Product's usage of the driver; Add the amounts from every pool to get the product's total overhead.
Overhead cost per unit: Overhead per unit = Total overhead assigned to the product ÷ Units produced; Add direct materials and direct labour for full unit cost.
Total product cost under ABC: Total cost = Direct costs + Σ (driver rate × driver usage); Σ means add up across all activity pools.

How to solve Activity Based Costing (ABC) questions

Use this method for any ABC calculation question. Keep each pool on its own line so you can check your working.

1List the overhead cost pools and the cost of each one.
2Identify the cost driver for each pool from the information given.
3Find the total volume of each driver across all products.
4Divide each pool cost by its total driver volume to get the driver rate.
5For each product, multiply each driver rate by that product's driver usage.
6Add the amounts across pools to get total overhead for each product.
7Divide by units produced to get overhead per unit, then add direct costs if the question asks for full unit cost.
8Check that total overhead assigned to all products equals total overhead in the pools.

Quickest way: Rate, usage, total check

When to use it: Use this in Section A number entry questions where you need one product's overhead or one driver rate and time is short.

Find the one pool the question asks about. Ignore the rest.
Divide that pool by the total driver volume across all products, not just the product in question.
Multiply by the product's driver usage.
Divide by units only if the question asks per unit.
Sense check: a product using more of the driver should get more cost.

Common mistakes in Activity Based Costing (ABC)

Dividing the pool cost by the driver volume of one product only
Students focus on the product named in the question and forget the rate must reflect total activity.
Fix: Always add driver volumes for all products first. The rate is the same for every product.
Choosing the wrong cost driver
Students pick the driver that sounds familiar, such as machine hours, instead of the one that causes the cost.
Fix: Ask what makes the cost rise. Inspection cost rises with the number of inspections, not with units made.
Forgetting to divide by units to get cost per unit
The calculation of total overhead for the product feels like the end of the question.
Fix: Re-read the requirement. If it says per unit, divide by units produced.
Using ABC and then still adding a volume-based absorption rate
Students are used to absorbing all overheads with one rate.
Fix: Under ABC, every overhead in a pool is assigned through its driver. Do not absorb the same cost twice.
Saying ABC always gives lower costs or higher profit
Students confuse more accurate with cheaper.
Fix: ABC changes how total overhead is shared between products. It does not change total overhead. Some products go up, others go down.
Claiming ABC suits every business
Students remember only the advantages.
Fix: State that it is most useful when overheads are high, products are varied and activity use differs from volume. Mention cost and complexity as limits.

Worked examples

Example 1

A company makes two products, X and Y. Overheads are: machine set-ups $60,000 and inspections $40,000. Product X needs 20 set-ups and 30 inspections. Product Y needs 40 set-ups and 20 inspections. X makes 1,000 units and Y makes 2,000 units. Calculate the overhead cost per unit of X and Y under ABC.

Show the solution

Total set-ups = 20 + 40 = 60. Set-up rate = $60,000 ÷ 60 = $1,000 per set-up.
Total inspections = 30 + 20 = 50. Inspection rate = $40,000 ÷ 50 = $800 per inspection.
Product X overhead = (20 × $1,000) + (30 × $800) = $20,000 + $24,000 = $44,000.
Product Y overhead = (40 × $1,000) + (20 × $800) = $40,000 + $16,000 = $56,000.
Check: $44,000 + $56,000 = $100,000, which equals $60,000 + $40,000.
Overhead per unit of X = $44,000 ÷ 1,000 = $44. Overhead per unit of Y = $56,000 ÷ 2,000 = $28.

Answer: Product X: $44 per unit. Product Y: $28 per unit.

Example 2

Using the same data, total direct labour hours are 5,000 for X and 5,000 for Y, so 10,000 in total. Calculate the overhead per unit of X under traditional absorption using direct labour hours, and say how it compares with the ABC figure.

Show the solution

Total overhead = $60,000 + $40,000 = $100,000.
Absorption rate = $100,000 ÷ 10,000 hours = $10 per direct labour hour.
Overhead absorbed by X = 5,000 × $10 = $50,000.
Overhead per unit of X = $50,000 ÷ 1,000 = $50.
ABC gave $44 per unit for X, so traditional absorption over-costs X by $6 per unit.
Reason: X uses fewer set-ups than its share of labour hours suggests, so volume-based absorption gives it too much overhead.

Answer: Traditional absorption gives $50 per unit for X, which is $6 higher than the ABC figure of $44.

Exam tips

In number entry questions, show the rate on your scratch pad first. A correct rate usually leads to a correct answer even if you slip later.
In multiple response questions, watch for statements that say ABC reduces total overheads or removes the need for judgement. Both are false.
Match the driver to the cost: set-ups for machine set-up cost, orders for purchasing cost, inspections for quality control, and deliveries for distribution.
Practise comparing ABC and traditional absorption results. Section A often tests which product gains or loses cost and why.
Know the limits well: cost of setting up the system, difficulty finding drivers for some overheads, and reliance on historical data.

Practice questions from Alternative cost accounting principles

Activity Based Costing (ABC) in other exams

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

Activity Based Costing (ABC): frequently asked questions

What is the difference between ABC and traditional absorption costing?

Traditional absorption uses one volume-based rate, such as per labour hour. ABC uses several rates, one for each activity, based on the cost driver for that activity. ABC usually gives a more accurate cost when products use activities in different proportions to volume.

What are examples of cost drivers in ACCA MA?

Common examples are the number of set-ups for set-up costs, the number of purchase orders for purchasing costs, the number of inspections for quality control, and the number of deliveries for distribution. Choose the driver that actually causes the cost to change.

Does ABC change total overheads?

No. Total overhead stays the same. ABC only changes how that total is shared between products. Some products receive more overhead and others receive less.

When is ABC most useful?

It is most useful when overheads are a large part of total cost, when products are varied or complex, and when different products use activities in different amounts. In a simple business with similar products, it may not be worth the cost.