Performance Management · Activity-based costing

Limitations of Traditional Absorption Costing in ACCA Performance Management

Updated 11 October 2026 · Fact-checked

Traditional absorption costing shares overheads using one volume-based rate, such as direct labour hours. This assumes overheads rise with volume. In modern firms, overheads are driven by activities like set-ups and orders. So high-volume products are overcharged, low-volume complex products are undercharged, and pricing and mix decisions go wrong.

Understand Limitations of Traditional Absorption Costing

Traditional absorption costing (TAC) works in three steps. You allocate and apportion overheads to cost centres. You calculate an absorption rate for each centre, usually per direct labour hour or machine hour. You then charge each product using that rate and the hours it uses.

This was reasonable when direct labour was the biggest cost and products were similar. Overheads were small, and labour hours were a fair guide to what a product consumed.

Today the picture is different. Overheads are often large because of automation, design, quality control, scheduling and distribution. Firms also make many products of different volumes and complexity. A volume-based rate ignores this.

The key idea is that overheads are caused by activities, not by volume. Setting up a machine costs the same for a batch of 10 units or 10,000. A low-volume product that needs many set-ups, inspections and special orders causes more overhead per unit. TAC spreads that cost across hours, so the high-volume product subsidises the low-volume one.

The result is cross-subsidisation. Reported product costs are wrong. Prices may be set too high for simple products, so you lose sales. Complex products look profitable when they are not. Decisions on mix, pricing and discontinuation are then based on poor data. Activity-based costing (ABC) tries to fix this by using cost pools and cost drivers that reflect what really causes each cost.

Key rules to remember

Traditional absorption rate: Absorption rate = Budgeted overhead for the cost centre ÷ Budgeted activity (e.g. direct labour hours); One volume-based rate per centre. It assumes overhead varies with the chosen volume measure.
Overhead charged to a product (TAC): Overhead per unit = Absorption rate × Hours per unit; Every unit with the same hours gets the same overhead, whatever its complexity.
ABC cost driver rate: Rate per driver = Cost pool ÷ Total cost driver units; Used to compare with TAC. Products are charged by the activities they actually use.
Direction of distortion: TAC cost < ABC cost → product undercosted; TAC cost > ABC cost → product overcosted; Usually low-volume, complex products are undercosted and high-volume, simple products are overcosted.

How to solve Limitations of Traditional Absorption Costing questions

Use this method for both written questions on the limitations of TAC and numerical questions that compare TAC with ABC.

1Read the scenario. Note the product range, volumes, complexity and the size of overheads compared with direct labour.
2For numbers, calculate the TAC rate: total overhead ÷ total hours (or other volume base). Then work out overhead per unit for each product.
3Identify the activities and cost drivers (set-ups, orders, inspections). Work out a rate for each cost pool.
4Calculate the ABC overhead per unit for each product by multiplying driver usage by the rates, then dividing by units.
5Compare the TAC and ABC figures. State which products are over- or under-costed and by how much.
6Explain why, in words: volume base does not reflect what causes cost, so there is cross-subsidisation.
7State the consequence for decisions: pricing, product mix, profitability analysis, discontinuation.
8If asked, mention that ABC also has limits, such as the cost and effort of collecting data.

Quickest way: Compare overhead per unit under each method

When to use it: Use when the question gives two or more products and asks you to show the effect of moving from TAC to ABC, or to comment on the difference.

Calculate TAC overhead per unit first. It is quick: rate × hours.
Calculate total ABC overhead by product, then divide by units.
Find the difference for each product. The sign tells you over- or under-costing.
Write one sentence naming the cause: the low-volume product uses more activities per unit than its labour hours suggest.
Add one sentence on the decision effect, such as prices set too low.

Common mistakes in Limitations of Traditional Absorption Costing

Saying TAC is wrong because it uses a rate at all.
Students confuse absorption with the choice of base.
Fix: Say the problem is the single volume-based driver. ABC also absorbs overheads, but with several drivers.
Stating that low-volume products are always undercosted by TAC.
It is the usual pattern, so it is memorised as a rule.
Fix: Calculate it. The result depends on activity usage per unit. Say 'typically' unless the numbers prove it.
Giving the limitation but not the consequence for decisions.
Students stop once the distortion is described.
Fix: Always add the effect: wrong selling prices, wrong mix decisions, wrong profitability or discontinuation choices.
Using total units instead of total driver units to find the ABC rate.
Rushing and mixing up the base.
Fix: Divide each cost pool by the total of its own driver, such as total set-ups or total orders.
Forgetting to convert ABC overhead to a per-unit figure before comparing with TAC.
ABC gives totals per product, TAC gives per-unit figures.
Fix: Divide ABC totals by units produced. Compare like with like.
Listing limitations without linking to the modern environment.
Answers are written as generic lists.
Fix: Link to high overheads, automation, product diversity and falling direct labour content.

Worked examples

Example 1

Z Ltd makes two products. Budgeted overhead is ₹6,00,000, absorbed on direct labour hours. Product A: 10,000 units, 1 hour each. Product B: 1,000 units, 1 hour each. Set-up costs of ₹3,00,000 are part of the overhead and are driven by the number of batches: A has 10 batches, B has 20 batches. The other ₹3,00,000 is driven by labour hours. Calculate the overhead per unit for each product under TAC and under ABC, and comment.

Show the solution

Total hours = 10,000 + 1,000 = 11,000.
TAC rate = ₹6,00,000 ÷ 11,000 = ₹54.5455 per hour. Overhead per unit is ₹54.55 for both A and B.
ABC: set-up rate = ₹3,00,000 ÷ 30 batches = ₹10,000 per batch.
Set-up cost: A = 10 × ₹10,000 = ₹1,00,000. B = 20 × ₹10,000 = ₹2,00,000.
Other overhead rate = ₹3,00,000 ÷ 11,000 hours = ₹27.2727 per hour. A = 10,000 × 27.2727 = ₹2,72,727. B = 1,000 × 27.2727 = ₹27,273.
Total ABC overhead: A = ₹1,00,000 + ₹2,72,727 = ₹3,72,727. B = ₹2,00,000 + ₹27,273 = ₹2,27,273.
ABC per unit: A = ₹37.27. B = ₹227.27.
Comparison: A is overcosted under TAC by ₹54.55 − ₹37.27 = ₹17.28 per unit. B is undercosted by ₹227.27 − ₹54.55 = ₹172.72 per unit.
Comment: B uses many batches for few units, so it causes more overhead per unit than hours suggest. TAC spreads set-up cost by volume, so A subsidises B.

Answer: TAC overhead is ₹54.55 per unit for both products. ABC overhead is ₹37.27 for A and ₹227.27 for B. TAC overcosts the high-volume product A and undercosts the low-volume, batch-heavy product B.

Example 2

A manufacturer's finance director says: 'Our overheads have risen from 10% to 45% of total cost, and we now sell 200 variants instead of 20. Our labour-hour absorption rate has not changed in method.' Explain why this raises concern about product costs and what the risks are.

Show the solution

Link the facts to the method. TAC uses a single volume base, such as labour hours, to share overheads.
Higher overheads mean any distortion in sharing them has a bigger effect on product cost.
More variants means more diversity in volume and complexity. Overheads like set-ups, design and inspection are driven by activities, not by labour hours.
So simple, high-volume variants are likely to be overcosted and complex, low-volume variants undercosted (cross-subsidisation).
Effects: selling prices for simple variants may be too high, losing sales; complex variants may be priced too low, giving hidden losses.
Mix and discontinuation decisions rely on distorted profits, and cost control is harder because activities are not visible.
Recommend considering ABC, which uses cost drivers that reflect activities, while noting that it costs more to run.

Answer: With overheads at 45% of cost and 200 variants, labour hours no longer explain overhead. TAC will cross-subsidise, so product costs, prices and mix decisions are likely to be wrong. ABC would give more accurate costs, at the price of more data collection.

Exam tips

In written parts, structure answers as cause, distortion, consequence. Three linked points score better than a list of five unexplained ones.
In numerical comparisons, show the TAC and ABC unit costs side by side and state the difference for each product.
Use the scenario facts. Mention the actual products, volumes, batch counts or overhead levels given.
In OT questions, watch for 'volume-based' and 'cross-subsidisation'. Options that claim TAC ignores overhead altogether are wrong.
Where a limitation of ABC is also asked, give a short balanced point, such as cost of data collection and arbitrary apportionment of some costs.

Practice questions from Activity-based costing

Limitations of Traditional Absorption Costing in other exams

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

Limitations of Traditional Absorption Costing: frequently asked questions

What are the main limitations of traditional absorption costing?

It uses one volume-based rate, so it ignores what really causes overhead. It also distorts product costs when overheads are large and products differ in volume and complexity. This leads to poor pricing and mix decisions.

Why is ABC better than traditional absorption costing?

ABC links overheads to activities through cost pools and cost drivers. Products are charged for the activities they use, so costs are usually more accurate. It also gives more insight for cost control, though it takes more effort to run.

What is cross-subsidisation in absorption costing?

It is when some products carry too little overhead and others carry too much. Typically high-volume simple products are overcharged and low-volume complex products are undercharged. Reported profits then mislead management.

Is traditional absorption costing ever suitable?

It can work where overheads are small, products are similar and volume is a reasonable guide to resource use. It is also simpler and cheaper to run. In exams, say it becomes less suitable as overheads and diversity grow.