Cost and Management Accounting · Activity Based Costing

Limitations of Traditional Costing and Need for ABC

Updated 4 October 2026 · Fact-checked

Traditional costing spreads all factory overheads using one volume-based rate, such as direct labour hours or machine hours. This over-costs high-volume simple products and under-costs low-volume complex ones. ABC fixes this by tracing overheads to activities first, then to products through cost drivers.

Understand Limitations of Traditional Costing and Need for ABC

Under traditional absorption costing, you collect overheads, apportion them to departments, and absorb them into products with one rate per department or per plant. The rate is usually based on direct labour hours, machine hours or direct wages. It is simple and cheap to run.

The weak point is the assumption behind it: overheads rise and fall with production volume. In a modern factory this is often untrue. Much overhead comes from setting up machines, inspecting, handling materials, scheduling, engineering changes and processing orders. These costs depend on the number and complexity of activities, not on how many units or hours a product uses.

So a product made in large batches with few set-ups gets the same overhead per labour hour as a product made in small batches with many set-ups. The simple product is over-costed and the complex product is under-costed. This is called cross-subsidisation. It leads to wrong selling prices, wrong product mix and wrong decisions to drop or push products.

The problem grew as direct labour shrank as a share of total cost and overheads grew, through automation, product variety and shorter product life. A rate on direct labour then loads a large overhead pool on a small base. Small errors in the base become large errors in product cost.

Activity Based Costing (ABC) was developed to fix this. It groups overheads into cost pools by activity, identifies the cost driver of each activity, and charges products by how much of each activity they use. The result is a more accurate cost, better pricing and better control of overheads.

Key rules to remember

Traditional overhead absorption rate: Rate = Total overheads ÷ Total base (labour hours, machine hours or direct wages); One rate for the plant or department. Overhead charged = Rate × base used by the product.
ABC cost driver rate: Cost driver rate = Cost of activity pool ÷ Total quantity of cost driver; Example: set-up cost ÷ number of set-ups. Different pools have different rates.
ABC overhead for a product: Overhead = Σ (Cost driver rate × Driver units used by the product); Add across all activity pools.
Distortion: Distortion = Traditional cost per unit − ABC cost per unit; Positive means the product was over-costed; negative means under-costed.

How to solve Limitations of Traditional Costing and Need for ABC questions

Use this for theory questions asking for limitations, need for ABC or comparison, and for short numericals showing distortion.

1Define traditional costing in one line: single volume-based rate, such as labour hours or machine hours.
2State the core assumption: overheads vary with volume. Then say why it fails: many overheads vary with activities such as set-ups, inspections and orders.
3Give the effect: simple, high-volume products are over-costed and complex, low-volume products are under-costed (cross-subsidisation).
4List consequences: wrong pricing, wrong product mix, wrong make-or-drop and poor overhead control.
5Explain the changed business setting: higher overheads, lower direct labour, more product variety, automation.
6State how ABC answers each point: activity pools, cost drivers, charging by consumption.
7For numericals, compute traditional cost, then ABC cost, then compare and comment on the over- or under-costing.

Quickest way: Rate, driver, compare

When to use it: Use when you have little time on a theory or short numerical question, including MCQs.

MCQ trick: if an option says traditional costing is 'more accurate' or 'uses many cost drivers', eliminate it. Traditional means one volume-based rate; ABC means many drivers.
Remember the pair: high volume and simple means over-costed under traditional; low volume and complex means under-costed.
For written answers use a two-column layout: Traditional costing versus ABC, with rows for basis, number of rates, overhead tracing, accuracy and cost.
For numericals, show the rate calculation line by line and write one comment line at the end. Step marks go to the working and the interpretation.
Always check that the overhead absorbed under both methods adds up to the same total. If not, you have made an error.

Common mistakes in Limitations of Traditional Costing and Need for ABC

Saying traditional costing ignores overheads.
Students confuse ignoring overheads with absorbing them on a poor basis.
Fix: Write that overheads are absorbed, but on a single volume-based rate that does not reflect resource consumption.
Reversing over-costing and under-costing.
Students do not link volume to the cost base.
Fix: High-volume products take a large share of the base, so they carry too much overhead. Low-volume complex products carry too little. Check with the totals.
Claiming ABC reduces total overhead.
Students think better costing means lower costs.
Fix: ABC changes how total overhead is spread, not its amount. Savings come only from decisions made using the better information.
Listing limitations without explaining them.
Students write a bare list in a rush.
Fix: Give each point a one-line reason, such as 'single rate, so set-up cost is charged by hours, not by number of set-ups'.
Using a different overhead total in the ABC calculation.
Students drop or double count a pool.
Fix: Add up all pools and agree the total to the overhead used in the traditional calculation.

Worked examples

Example 1

A firm has total overheads of ₹6,00,000, absorbed on direct labour hours. Product A uses 8,000 hours and Product B uses 4,000 hours. Of the overheads, ₹3,60,000 relates to set-ups, which total 60 (A: 10, B: 50). The remaining ₹2,40,000 varies with labour hours. Show how traditional costing distorts the overhead charged to A and B.

Show the solution

Traditional rate = ₹6,00,000 ÷ 12,000 hours = ₹50 per hour.
Traditional overhead: A = 8,000 × ₹50 = ₹4,00,000. B = 4,000 × ₹50 = ₹2,00,000.
ABC set-up rate = ₹3,60,000 ÷ 60 = ₹6,000 per set-up. A = 10 × ₹6,000 = ₹60,000. B = 50 × ₹6,000 = ₹3,00,000.
Hour-based rate = ₹2,40,000 ÷ 12,000 = ₹20 per hour. A = 8,000 × ₹20 = ₹1,60,000. B = 4,000 × ₹20 = ₹80,000.
ABC overhead: A = ₹60,000 + ₹1,60,000 = ₹2,20,000. B = ₹3,00,000 + ₹80,000 = ₹3,80,000. Total = ₹6,00,000, which agrees.
Distortion: A = ₹4,00,000 − ₹2,20,000 = ₹1,80,000 over-costed. B = ₹2,00,000 − ₹3,80,000 = ₹1,80,000 under-costed.

Answer: Traditional costing over-costs A by ₹1,80,000 and under-costs B by the same amount. B is the complex product with many set-ups, so A subsidises B.

Example 2

Explain why traditional absorption costing may give misleading product costs and why ABC was developed.

Show the solution

Define: traditional costing absorbs overheads using a single volume-based rate, such as labour or machine hours.
Assumption: overheads vary with volume. This is weak when overheads come from activities such as set-ups, inspection, material handling and order processing.
Effect: high-volume simple products are over-costed and low-volume complex products are under-costed. This is cross-subsidisation.
Business impact: wrong pricing, wrong product mix and wrong make-or-drop decisions. The firm may lose profitable products and keep loss-making ones.
Changed environment: overheads are now a larger share of cost, direct labour is smaller, and product variety and automation have grown. A labour-hour rate loads big overheads on a small base.
Response: ABC traces overheads to activity pools, finds a cost driver for each pool and charges products by their use of activities.

Answer: Traditional costing distorts product cost because one volume-based rate ignores what actually causes overheads. ABC was developed to charge overheads by activity consumption, giving more accurate costs for pricing and decisions.

Exam tips

For a 'differentiate' question, use a two-column format with at least five rows: basis of charging, number of rates, cost drivers, accuracy and suitability.
In numericals, show both methods side by side and end with a one-line comment on which product is over-costed or under-costed.
Check that ABC and traditional overhead totals agree before you finish.
In theory answers, link each limitation to its consequence, such as wrong pricing. This earns more than a bare list.
MCQs often test who gets over-costed under traditional costing. Answer: the high-volume, simple product.

Practice questions from Activity Based Costing

Limitations of Traditional Costing and Need for ABC 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 Costing and Need for ABC: frequently asked questions

What is the main limitation of traditional costing?

It uses one volume-based rate to absorb all overheads. Many overheads depend on activities, not volume, so product costs become distorted. Simple high-volume products are over-costed and complex low-volume ones are under-costed.

How is ABC different from traditional costing?

Traditional costing absorbs overheads with one or a few volume-based rates. ABC groups overheads into activity pools and charges them using cost drivers based on actual consumption. This gives more accurate product costs.

Does ABC change the total overhead of the firm?

No. The total overhead absorbed is the same under both methods. Only the split between products changes.

Why is ABC important now and not earlier?

Overheads have grown as a share of total cost, while direct labour has fallen. Product variety and automation have also increased. A single labour-based rate then gives large distortions.