Learning objectives
By the end of this chapter you should be able to:
- Explain why traditional overhead absorption can misstate product costs when overheads are significant and products consume support activities in different proportions.
- Calculate activity rates and apply activity-based costing (ABC) to derive more representative product costs, then interpret the reasons for cost shifts.
- Calculate a target cost from a target selling price and required profit, and explain practical methods to close a cost gap while protecting customer value.
- Prepare a simple life-cycle cost view and use it to compare design, production, and after-sales choices.
- Link modern cost management information to pricing, product design, process improvement, and performance evaluation.
Overview & key concepts
Many organisations now operate with high indirect costs (planning, engineering, quality, logistics, customer support) and relatively lower direct labour content. In these environments, a single overhead absorption base (for example, labour hours) can produce “reasonable-looking” product costs that still mislead decision-making.
Modern cost management techniques improve decisions by making resource consumption more visible:
- ABC improves how overheads are traced to products or services by using multiple activity-based cost drivers.
- Target costing starts from the price the market will accept and works backwards to the maximum cost that still delivers the required profit.
- Life-cycle thinking broadens the analysis beyond manufacturing to include costs incurred before launch and after sale.
These methods are primarily internal tools. They do not change total overhead spending in a period, but they can change how costs are attributed to products, which can materially affect pricing, product mix, and improvement priorities.
A useful way to link the three approaches is by timing and purpose:
- ABC explains where overhead resources are being consumed and by which products (diagnosis and costing).
- Target costing uses market constraints to set an allowable cost before launch (planning and design control).
- Life-cycle thinking ensures decisions are evaluated across the product’s whole economic impact, not only the factory stage (long-term optimisation).
Activity-Based Costing (ABC)
What ABC is trying to fix
Traditional absorption costing often uses one volume-based driver (such as units, labour hours, or machine hours). This works best when overheads are small relative to direct costs and products are broadly similar in how they use support activities.
When products differ in complexity, batch sizes, set-up requirements, quality checks, or material movements, a single driver tends to over-cost high-volume simple products and under-cost low-volume complex products.
ABC reduces this distortion by recognising that different overheads are driven by different activities.
How ABC works (in brief)
ABC usually follows four practical steps:
- Identify key activities that consume indirect resources.
- Create cost pools for each activity.
- Select cost drivers that best represent the cause of each activity cost.
- Calculate activity rates and assign overheads based on each product’s driver usage.
When ABC is useful (and when it may add little)
ABC is typically most valuable where you see one or more of these cues:
- overheads are large compared with direct costs
- many different products, variants, or customer requirements
- frequent set-ups, short runs, or high engineering/quality effort
- strong suspicion that “simple” products are subsidising “complex” ones
It may add less value where output is homogeneous, overhead is small and stable, or a single driver already reflects consumption reasonably well.
A practical warning: do not over-engineer the model. The goal is better decisions, so pools and drivers should be chosen on materiality and usefulness, not perfection.
Where ABC can be used — and where it shouldn’t be over-read
ABC is mainly a management tool: it helps explain which activities are consuming support resources and why one product may be “heavier” on set-ups, purchasing, inspection, or handling than another.
If ABC outputs are used for external product cost figures, keep the boundary clear. Only include costs that relate to making goods ready for sale (direct materials, direct labour, and production support). Activities linked to selling, marketing, and delivering to customers are treated as period costs rather than being attached to inventory values. Also be careful not to treat inefficiency as an asset: if volumes are unusually low or there is abnormal waste, the extra overhead and waste-related costs should be reported in the period rather than being absorbed into inventory.
Even when ABC is used, remember the headline interpretation: total production overhead spending does not change — ABC changes the pattern of attribution across products, which can affect decisions and (where inventories exist) the split between inventory and cost of sales.
Target costing
Core idea
Target costing is a design-and-planning discipline:
- Determine a target selling price driven by customer expectations and competitor offerings.
- Decide the required profit (often expressed as a percentage of selling price).
- Compute the target cost:
Target cost = Target price − Required profit
If the estimated cost of the proposed design is higher than the target cost, there is a cost gap that must be closed before launch.
Closing a cost gap without destroying value
Cost reduction in target costing focuses on removing cost that customers do not value, rather than stripping features indiscriminately. Common approaches include simplifying product architecture, reducing part variety, improving manufacturability, collaborating with suppliers, and standardising where it does not affect the buying decision.
Practical note: in target costing, the “estimated cost” is normally built from the proposed design and process plan (materials, routings, supplier quotations, expected yields). ABC is often used to strengthen the overhead/resource assumptions within that estimate.
Execution point: target costing works best as a cross-functional process, with design, procurement, production, and marketing sharing ownership of the cost gap and agreeing trade-offs.
Life-cycle costing and life-cycle thinking
Why life-cycle costs matter
A significant share of total economic cost can arise outside the factory: design and development, testing, launch support, warranties, returns, service, and end-of-life obligations. Focusing only on manufacturing cost can push decisions that look favourable today but create higher costs later.
A simple life-cycle cost view
A practical structure is to group costs into:
- design and development
- production and distribution
- after-sales support and end-of-life
Life-cycle costing is not about forcing costs into a neat pattern over time. It is about ensuring decisions consider all costs caused by a product over its life, wherever they occur.
Cost drivers and activity rates
Cost drivers
A cost driver is a measurable factor used to assign activity costs to cost objects (products, services, customers). Good drivers have a clear cause-and-effect link with the activity, are practical to measure reliably, and encourage sensible behaviour.
Activity rates
An activity rate is:
Activity rate = Total cost in pool ÷ Total driver volume
Example: a set-up pool of £30,000 with 60 set-ups gives £500 per set-up.
Capacity, “fixed” overhead, and interpretation discipline
Not all overhead costs rise and fall with the chosen driver in the short term. Some costs represent capacity provided (for example salaried staff or owned equipment). If driver volume falls, a calculated rate can rise even though the underlying spend is unchanged.
For short-term decisions, treat ABC rates carefully: focus on whether costs are avoidable in the decision timeframe, separate the cost of unused capacity where practical, and avoid pricing decisions that mechanically “recover” unused capacity through higher product costs.
Value engineering and continuous improvement
Value engineering
Value engineering is structured redesign aimed at maintaining required functionality and perceived value while reducing cost. It is most effective before the product is finalised, when specifications and processes can still change materially.
Kaizen costing (continuous improvement)
After launch, many organisations pursue incremental cost reductions through ongoing process improvement (layout changes, set-up time reduction, defect prevention, waste elimination). The emphasis is small, repeated gains rather than one-off redesign.
Worked example
Narrative scenario
XYZ Ltd manufactures two products: Product A and Product B. Management currently uses a traditional absorption approach but is considering ABC to improve cost visibility.
During the period:
- Direct materials and labour
- Overhead activities and totals
- Activity usage by product
- Target costing data
- Life-cycle information (definition for this question)
Required
- Calculate the activity rates for set-ups, inspections, and material handling.
- Assign overheads to Product A and Product B using ABC.
- Determine the manufacturing full cost per unit for each product using ABC.
- Calculate the target cost and the cost gap (or cost headroom) for each product.
- Calculate the non-manufacturing life-cycle cost per unit for each product.
- Propose actions to close the cost gap for Product B, taking life-cycle costs into account.
Solution
1) Activity rates
- Set-up rate = £30,000 ÷ 60 = £500 per set-up
- Inspection rate = £20,000 ÷ 400 = £50 per inspection
- Handling rate = £10,000 ÷ 250 = £40 per move
2) Overheads assigned using ABC
Product A
- Set-ups: 20 × £500 = £10,000
- Inspections: 100 × £50 = £5,000
- Moves: 150 × £40 = £6,000
- Total overhead for A = £21,000
Product B
- Set-ups: 40 × £500 = £20,000
- Inspections: 300 × £50 = £15,000
- Moves: 100 × £40 = £4,000
- Total overhead for B = £39,000
Check: £21,000 + £39,000 = £60,000, which equals total overhead (£30,000 + £20,000 + £10,000).
3) Manufacturing full cost per unit using ABC
Overhead per unit:
- Product A: £21,000 ÷ 1,000 = £21 per unit
- Product B: £39,000 ÷ 200 = £195 per unit
Full manufacturing cost per unit:
- Product A: £18 + £12 + £21 = £51
- Product B: £22 + £18 + £195 = £235
Interpretation: Product B absorbs far more overhead per unit because it consumes a disproportionate share of set-ups and inspections relative to its low volume.
4) Target cost and cost gap (or headroom)
Required profit is 20% of target price:
Product A
- Target price = £120
- Required profit = 20% × £120 = £24
- Target cost = £120 − £24 = £96
- Estimated manufacturing cost per unit (approximated here by the ABC unit cost) = £51
- Cost headroom = £96 − £51 = £45
Product B
- Target price = £150
- Required profit = 20% × £150 = £30
- Target cost = £150 − £30 = £120
- Estimated manufacturing cost per unit (approximated here by the ABC unit cost) = £235
- Cost gap = £235 − £120 = £115
5) Non-manufacturing life-cycle cost per unit
- Product A: £200,000 ÷ 5,000 = £40 per unit
- Product B: £100,000 ÷ 2,000 = £50 per unit
Average whole-life cost per unit (based on expected volumes)
Because the life-cycle figures and expected units are forecasts, the following is an average whole-life cost per unit based on expected volumes; the average will change if actual lifetime volumes differ.
- Product A: manufacturing £51 + non-manufacturing £40 = £91 per unit (average)
- Product B: manufacturing £235 + non-manufacturing £50 = £285 per unit (average)
6) Actions to close the cost gap for Product B (with life-cycle focus)
A cost gap of £115 per unit is substantial. Actions should target the main drivers of the high ABC cost (set-ups and inspections) and the post-sale costs flagged by the warranty concern.
Reduce set-ups and inspection effort
- Reduce changeovers by scheduling and standard tooling; invest in faster changeovers to cut set-up time and frequency.
- Reduce inspection demand by improving process capability and first-pass quality (prevention rather than repeated checking).
Redesign to remove complexity (value engineering)
- Simplify Product B’s design to reduce part count and assembly steps, which typically lowers defects, inspections, and handling.
- Standardise components where it does not reduce customer value.
- Work with suppliers on specification changes that preserve function but reduce total cost.
Attack warranty and service costs (life-cycle leverage)
- Redesign failure-prone components using warranty/returns data to target the biggest drivers of claims.
- Improve robustness where the reduction in warranty and service costs over the product’s life exceeds any increase in manufacturing cost.
- Improve packaging/handling design to reduce damage-related claims.
Exam-appropriate interpretation cues
When interpreting results, structure conclusions in two steps:
- Explain the cost shift (which activities and drivers are responsible, and why the product consumes them).
- State decision implications (pricing, product mix, and where process/design effort should focus).
For this scenario: Product B is the complexity-heavy product; it should trigger targeted redesign and process changes rather than a simple volume-based cost recovery approach.
Common pitfalls and misunderstandings
- Treating ABC rates as automatically variable costs. Many overheads relate to capacity; short-term decisions should focus on avoidable costs and constraints.
- Choosing drivers for convenience rather than causality. A driver that is easy to measure but weakly linked to the activity creates a new distortion.
- Using too many pools and drivers. Overly complex models can become costly to maintain and can distract from the main cost drivers.
- Ignoring low-volume complexity. Small product lines can consume disproportionate support effort; ABC often reveals this.
- Misstating the cost gap direction. A gap exists when estimated cost is above target cost; when cost is below target, the difference is headroom.
- Cost reduction that damages value. Removing features customers care about can reduce price and volume, defeating the purpose of target costing.
- Manufacturing-only focus. A design that is cheap to make can be expensive to support; life-cycle thinking prevents false economies.
Summary and further reading
ABC, target costing, and life-cycle thinking address common weaknesses in traditional overhead absorption:
- ABC improves cost attribution by linking overheads to the activities products actually use, highlighting complexity and support effort.
- Target costing starts from a market price and required profit to set an allowable cost, then uses value-focused redesign to close any cost gap.
- Life-cycle thinking broadens attention beyond manufacturing to include design and after-sales costs, supporting better long-term decisions.
Together they strengthen pricing, product design choices, process improvement priorities, and strategic resource allocation.
FAQ
Why does ABC often increase the reported cost of low-volume products?
Low-volume products can require frequent set-ups, more quality checks, special handling, and more engineering support. Traditional single-rate absorption can hide that complexity by spreading overhead mainly on volume. ABC makes those support costs visible by assigning them using activity usage.
If ABC is “better”, why doesn’t every organisation use it?
ABC requires data collection, maintenance, and periodic review. If products are similar and overhead is relatively small, the benefits may not justify the effort. Many organisations apply ABC selectively to the biggest overhead areas rather than building a full model.
In target costing, should profit be based on a percentage of selling price or cost?
Either can be used, but it must be applied consistently with how performance is measured. Profit as a percentage of selling price is common in target costing because it links directly to market pricing and margin expectations.
How does life-cycle thinking affect design decisions?
It encourages decisions that minimise total cost over the product’s life, not just manufacturing cost. For example, higher-quality components may raise build cost but reduce warranty claims, repairs, and returns.
Can a product be viable even if manufacturing cost is above target cost?
Potentially, but only if the business can justify a higher price, accept a lower profit, or expects reductions through redesign and continuous improvement. Where market price is fixed and the gap is large, redesign is usually essential before launch.
Glossary
Activity-Based Costing (ABC)
A method of attributing overheads to products or services using activity cost pools and cost drivers that reflect resource usage.
Activity
A process or task that consumes indirect resources (for example set-ups, inspections, material handling).
Cost pool
A collection of overhead costs associated with a particular activity.
Cost driver
A measurable factor used to assign activity costs to products or services (for example number of set-ups, inspections, or moves).
Activity rate
Cost per unit of driver, calculated as total pool cost divided by total driver volume.
Cost object
Anything for which a cost is measured (such as a product, service line, customer segment, or contract).
Cost distortion
A misstatement of product or service costs caused by using an allocation approach that does not reflect real resource consumption.
Target price
The selling price that is feasible in the market for the required features and quality level.
Target cost
The maximum allowable cost that still delivers the required profit at the target price.
Cost gap / cost headroom
Cost gap: estimated cost above target cost (a required reduction).
Cost headroom: estimated cost below target cost (room available for design choices, investment, or margin protection).
Value engineering
Structured redesign to reduce cost while maintaining required functionality and customer value.
Kaizen costing (continuous improvement)
Ongoing incremental cost reduction through process improvements during production and delivery.
Life-cycle costing
Assessment of total non-manufacturing costs caused by a product across its life (for example design and after-sales), used alongside manufacturing cost to support whole-life decisions.