Management Accounting · Cost accounting methods

Service Costing and Composite Cost Units in ACCA Management Accounting

Updated 11 October 2026 · Fact-checked

Service costing finds the cost of providing a service, not a physical product. Because services are intangible, you use a composite cost unit such as cost per passenger-mile or per patient-day. Add up the total cost for the period, then divide by the number of composite units achieved.

Understand Service Costing

Service costing is used by organisations that sell services, such as transport firms, hospitals, hotels, schools and call centres. There is no physical output to count, so you cannot simply cost one unit of product.

Services have four typical features: they are intangible, they cannot be stored (perishable), they are produced and used at the same time (simultaneity), and each service can vary (heterogeneity). Because of these, costs are mostly fixed or semi-fixed and there is usually no closing inventory of finished goods.

To get a useful unit cost, you use a composite cost unit. This combines two measures into one. A bus company uses passenger-miles (passengers carried × miles travelled). A hospital uses patient-days. A hotel uses occupied room-nights. A haulage firm uses tonne-miles. The composite unit reflects both the volume and the distance or time of the service.

The main difference from product costing is the cost unit and the cost mix. Product costing (job, batch, process) tracks materials, labour and overheads into physical units, with inventory valuation. Service costing has little or no inventory and a high share of fixed costs, so the key task is choosing a sensible unit and collecting costs accurately.

Costs are often grouped by nature, for example fixed (depreciation, insurance, road tax) and running or variable costs (fuel, repairs). Managers use the cost per unit to set prices, compare periods or routes, and control costs.

Key formulas to remember

Cost per composite unit: Cost per unit = Total costs for the period ÷ Number of composite units; Use total costs of the service for the same period and the same service as the units.
Passenger-miles: Passenger-miles = Number of passengers × Miles travelled; Sum across trips if passenger numbers differ by trip. Do not average blindly.
Average passengers carried: Passenger-miles ÷ Miles run = Average passengers per mile; Useful when the question gives total passenger-miles and vehicle miles.
Tonne-miles: Tonne-miles = Tonnes carried × Miles travelled; For a round trip with an empty return, only count the loaded leg unless told otherwise.
Occupancy rate: Occupancy % = Units used ÷ Units available × 100; Example: rooms occupied ÷ rooms available. Also applies to bed-days and seat-miles.

How to solve Service Costing questions

Use this method for any service costing question, whatever the industry.

1Read the question and identify the service and the best composite cost unit (for example patient-day, passenger-mile, tonne-mile).
2List all the costs given and check they relate to the service and the period asked about.
3Add up the costs. If asked, split them into fixed and variable.
4Calculate the number of composite units. Multiply the two measures, such as passengers × miles, or beds × days occupied.
5Watch the units: use units actually achieved or occupied, not capacity, unless the question asks for capacity.
6Divide total cost by composite units to get cost per unit.
7If asked for a price, add the profit mark-up or margin to the cost per unit.
8Check the answer is sensible and give it in the form asked (decimals, currency, rounding).

Quickest way: Total cost over composite units

When to use it: Use for number-entry questions where costs and activity are given directly and no cost splitting is needed.

Underline the cost unit asked for in the question.
Add all costs in one go on the calculator.
Compute units as the product of the two measures, using actual activity.
Divide and round only at the end.
Sanity check: does the answer look similar in size to the cost per unit of typical routes or wards?

Common mistakes in Service Costing

Using capacity instead of actual activity in the divisor
Questions give both available and used figures, and students pick the larger one.
Fix: Divide by units actually achieved (occupied bed-days, passengers carried) unless the question says to use capacity.
Choosing the wrong composite unit
Students pick one measure only, such as miles, and ignore passengers or weight.
Fix: Match the unit to the service and make it combine volume and distance or time, such as passenger-miles or tonne-miles.
Counting the empty return journey in tonne-miles
Students multiply tonnes by total miles out and back.
Fix: Count loaded tonnes only for the miles loaded, unless the question defines the unit differently. Costs still include the whole journey.
Leaving out fixed costs such as depreciation or insurance
Students focus on running costs like fuel and repairs.
Fix: Include all costs of the service for the period, then divide. Check every item in the list.
Mixing periods, such as annual costs with monthly activity
Data is given in different time frames.
Fix: Convert costs and activity to the same period before dividing.
Treating service costing as having closing inventory
Habit from product costing.
Fix: Services are perishable, so normally no inventory is valued. All period costs are charged to the service.

Worked examples

Example 1

A bus operator runs one route. In a month it incurs fuel $4,200, driver wages $9,000, depreciation $3,600 and insurance $1,200. The bus ran 6,000 miles and carried an average of 20 passengers per mile. Calculate the cost per passenger-mile.

Show the solution

Total costs = 4,200 + 9,000 + 3,600 + 1,200 = $18,000.
Passenger-miles = 6,000 miles × 20 passengers = 120,000.
Cost per passenger-mile = 18,000 ÷ 120,000 = $0.15.

Answer: $0.15 per passenger-mile

Example 2

A hospital ward has 25 beds and is open for 30 days in a month. Occupancy is 80%. Monthly ward costs are $90,000. Calculate the cost per patient-day.

Show the solution

Available bed-days = 25 × 30 = 750.
Occupied bed-days = 750 × 80% = 600.
Cost per patient-day = 90,000 ÷ 600 = $150.

Answer: $150 per patient-day

Exam tips

Read the last line first to see which cost unit is required, then work backwards.
In multiple response questions, pick the true statements about services: intangibility, perishability, no inventory, and use of composite units.
For number entry, check rounding instructions and whether the answer should be in dollars or cents.
Beware of averages: if passenger numbers vary by trip, compute passenger-miles trip by trip.
Know examples by heart: passenger-mile for transport, patient-day for hospitals, occupied room-night for hotels, tonne-mile for haulage.

Practice questions from Cost accounting methods

Service Costing in other exams

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

Service Costing: frequently asked questions

What is a composite cost unit?

A composite cost unit combines two measures to describe a service, such as passenger-miles or patient-days. It reflects both how much service is given and the distance or time involved. It is common where a single measure would be misleading.

What is the difference between service costing and product costing?

Product costing values physical output and usually tracks materials, labour and overheads into inventory. Service costing deals with intangible output that cannot be stored, so there is typically no inventory. It uses composite cost units and often has a high proportion of fixed costs.

Which industries use service costing?

Transport, hospitals, hotels, schools, catering, banks and call centres commonly use it. Internal services such as canteens or maintenance departments can also be costed this way.

Should I use available or actual units for cost per unit?

Use actual units achieved, such as occupied bed-days or passengers carried, unless the question asks about capacity. Using capacity understates the true cost per unit of service delivered.