What it means
Cost accounting begins with a question: what do we want to know the cost of? The answer is the cost object.
For a manufacturer the obvious objects are products; for a contractor, jobs; for a consultancy, engagements; for a hospital, patients and procedures; for a retailer, stores and categories; for any business with a sales force, customers. Most businesses need several, because decisions are made at several levels: pricing needs product costs; account management needs customer costs; budgeting needs departmental costs; investment needs project costs.
Once the objects are chosen, every cost is either direct or indirect relative to each. A direct cost can be traced to the object economically and unambiguously: the steel in a product, the hours a consultant charged to an engagement, the delivery to a customer.
An indirect cost benefits several objects and must be allocated: factory rent across products, the sales office across customers, head office across business units. The same cost can be direct to one object and indirect to another: a production supervisor's salary is direct to the production department (a cost object) and indirect to each product made there.
The design question is therefore not only which objects to cost but how far to trace: tracing is more accurate than allocation but costs more to do, and the system stops where the added precision is worth less than its cost. Hierarchies of cost objects are common.
Products roll up into product lines and into business units; customers into segments and channels; jobs into contracts and clients; departments into functions and sites. Costs traced or allocated at one level aggregate to the next, and a well-designed system lets management see the cost of a single product and of the whole line, of one customer and of the channel, without rebuilding the analysis.
The choice of cost objects reflects and shapes management attention. A business that costs only products will manage products and be blind to the fact that half its customers lose it money; adding customers as cost objects reveals the cost to serve and changes the sales strategy.
A business that costs only departments will manage budgets and be blind to the cost of the processes that cross them; adding processes as cost objects reveals the cost of order-to-cash or procure-to-pay and directs improvement. A business that costs projects sees which succeed; one that does not cannot tell.
The limits are practical. Every cost object requires data collection (time recording, transaction coding, allocation bases) and maintenance, and a system with too many objects collapses under its own weight or is populated with allocations so arbitrary that the results mean nothing.
The right set is the one that supports the decisions the business actually makes, revisited as those decisions change.
In practice
Real-world examples.
Example
A hospital costs each patient episode by tracing theatre time, drugs, tests and bed-days and allocating ward and departmental overhead, comparing the result with the tariff paid.
Example
A bank treats each product, each customer segment and each branch as cost objects and finds that its small business current account is unprofitable in every branch.
Example
A construction company's cost objects are contracts, with costs traced from timesheets, material requisitions and subcontractor certificates, and overhead allocated by contract value.
Think of it
“A cost object is whatever you're trying to figure out the cost of-products, customers, projects.
Formula
Calculation
Cost of a cost object = Direct costs traced to it + Indirect costs allocated to it
Direct cost tracing: Cost x (Units or hours consumed by the object)
Indirect cost allocation: Cost pool x (Object's share of the allocation base)
Profitability of a cost object = Revenue attributable to it minus Its cost (full or contribution basis, as the decision requires)
Worked example. A specialist engineering firm defines four cost objects for its management accounts: projects, clients, service lines and the firm's two offices. A project in the year:
Project P-214, a plant automation design for Client K, delivered by the Controls service line from the northern office. Revenue $180,000.
Direct costs traced to the project: engineering hours 620 at loaded rates averaging $95 = $58,900; subcontracted software development $22,000; travel and site expenses $6,400; specialist software licence for the project $3,500. Direct total $90,800.
Indirect costs allocated to the project: service line overhead (Controls: technical management, tools, training; $420,000 across 7,000 chargeable hours in the line) at $60 per hour = $37,200; office overhead (northern office rent, support staff, IT; $900,000 across 15,000 chargeable hours) at $60 per hour = $37,200; firm overhead (management, finance, marketing, insurance; $1,200,000 across 30,000 firm-wide chargeable hours) at $40 per hour = $24,800. Allocated total $99,200.
Full cost $190,000. Project margin: minus $10,000 (minus 5.6%). Contribution basis (revenue less direct costs): $89,200 (49.6%).
The project looks loss-making at full cost and healthy at contribution. Which is right depends on the decision: for pricing future similar projects, the full cost says the firm should quote higher or deliver in fewer hours (the project overran its 500-hour estimate); for deciding whether to have taken the project when the office had spare capacity, the contribution says yes.
Same costs, different object: Client K. The firm delivered four projects for Client K in the year: revenue $520,000; direct costs $270,000; allocated overhead $260,000; full-cost margin minus $10,000; contribution $250,000. Client-level direct costs not traceable to any project: an account manager's time, 200 hours at $110 = $22,000; a client entertainment budget $4,000; two proposals that were not won, 90 hours = $8,550. Client K's cost includes $34,550 that no project carries. Client contribution after client-specific costs: $215,450 (41%). Client K is a good client whose projects are consistently under-estimated; the answer is better estimating, not fewer projects.
Same costs, different object: the Controls service line. Revenue $1,100,000 across 24 projects; direct costs $560,000; line overhead $420,000; contribution after line overhead $120,000. The line's 7,000 chargeable hours carry office overhead at $60 ($420,000) and firm overhead at $40 ($280,000): $700,000 in total, so the full-cost result is a loss of $580,000. The service line's problem is utilisation: its seven engineers have 12,600 available hours and charged 7,000 (56%); the line overhead and its share of office and firm overhead are spread over too few chargeable hours. Raising utilisation to 70% (8,820 chargeable hours, 1,820 more) at the same rates would add about $286,000 of revenue at almost no additional cost.
Same costs, different object: the northern office. Revenue $3,600,000; direct costs $1,900,000; office overhead $900,000; allocated firm overhead $600,000; profit $200,000 (5.6%). The southern office shows 14%. The northern office's low utilisation in Controls is the main cause.
Four cost objects, four views of the same costs, and four different decisions: re-estimate project types; keep the client; fix the line's utilisation; investigate the office. A system that costed only projects would have flagged P-214 as a loss and stopped there.Case study
Seen in the real world.
A food manufacturer's costing system had products as its only cost objects. Product margins were reported monthly and the sales team was managed on volume. When margins fell for two years despite stable product costs, the finance director added customers as cost objects: for each of the 150 customers, the costs of order handling, delivery (by drop size and distance), promotional support, returns, credit and account management were traced or allocated.
The result was that the three largest customers, 45% of revenue, absorbed 70% of the cost to serve through daily deliveries, promotional funding, extended credit and returns, and were marginally profitable; the middle tier of 40 customers was highly profitable; and 60 small customers lost money on every order. The company had been growing its least profitable customers because they bought the most. It renegotiated delivery frequency and promotional terms with the largest customers, set minimum order values and a delivery charge for small ones (losing 25 of the 60, unmissed), and redirected its sales effort to the middle tier.
Margin recovered by four points in eighteen months with no change in product costs. The finance director's note observed that the company had known the cost of everything it made and nothing about the cost of anyone it sold to.
Watch out
Common mistakes.
- Costing only products (or only departments) and so being unable to see the profitability of customers, channels, projects or processes where the decisions actually lie.
- Treating a cost as direct or indirect in the abstract, when the classification depends on the cost object chosen.
- Multiplying cost objects and allocations until the system is too expensive to maintain and its results too arbitrary to trust.
Questions
People also ask.
What is the difference between a cost object and a cost centre?
A cost centre is a type of cost object (a department or unit responsible for costs). Cost objects are broader: anything whose cost is measured, including products, customers, projects and activities.
How do I decide which cost objects to use?
Start from the decisions the business makes (pricing, customer terms, project selection, budgeting, outsourcing) and choose the objects those decisions need. Add objects when a decision requires them, not before.
Can a cost be direct to two cost objects at once?
Yes. A delivery to a customer of a single product is direct to the product, the customer, the order and the region. The tracing is the same; the objects are different views.
From the founder's library
Take it further with the book.
Build your financial confidence beyond this definition. Shihan's full-length guide, Accounting Fundamentals, takes the same plain-English approach and turns it into a complete, practical playbook for non-finance managers, business owners and students - with chapter-end quiz answers and presentation slides included.
25% off with code MMHQ25, applied at checkout. Priced in USD - checkout may show the equivalent in your local currency.
View the book and save 25%