Activity Based Costing (ABC): What It Is, How It Works, and Why It Matters | Accounting Management
What Is Activity Based Costing?
Activity based costing (ABC) is a managerial accounting method that assigns overhead and indirect costs to products or services based on the specific activities required to produce them. It focuses on the cause and effect relationship between costs and the activities that drive them.
The ABC method was developed in the United States. Robert Kaplan is regarded as the founder of the theoretical principles of activity based costing within the cost management knowledge area. In the 1970s, the ABC method was introduced in the manufacturing industry to solve the problems of traditional cost price calculation.
Activity based costing is a concept that was introduced in 1971 by George J. Staubus of the Haas School of Business at the University of California, Berkeley. It was not until 1986 when Robert S. Kaplan and William J. Bruns of the Harvard Business School published a formal definition for ABC.
The core idea is simple: costs are caused by activities, and products consume those activities. If a product requires more machine setups, more quality checks, or more engineering time, it should carry more of those costs, not just a proportional share based on labor hours.
Key Terms to Know
| Term | Definition |
|---|---|
| Cost Pool | A group of overhead costs tied to a single activity (e.g., machine setup costs) |
| Cost Driver | The factor that causes a cost to change (e.g., number of setups, labor hours) |
| Activity Rate | The cost per unit of a cost driver (Total Cost Pool / Total Cost Drivers) |
| Overhead | Indirect costs not directly tied to one product (e.g., rent, utilities, supervision) |
| Cost Object | The product, service, or customer that is being costed |
How ABC Works: Step by Step
Here is a breakdown of the steps that go into activity based costing: identify all the activities that go into creating a product, separate each activity into groups (e.g., product line), assign activity cost drivers to each group, divide the total overhead in each group by the total activity cost drivers to get the cost driver rate, and multiply the cost driver rate by the amount of activity cost drivers.
Step 1: Identify All Activities
List every activity involved in making the product. Examples: machine setup, quality inspection, order processing, material handling.
Step 2: Group Activities into Cost Pools
Activities like machine maintenance, quality control, and assembly might all fall under a production cost pool.
Step 3: Identify a Cost Driver for Each Pool
A cost driver is whatever actually causes that pool of costs to grow or shrink. For machine setup costs, the cost driver might be the number of production runs.
Step 4: Calculate the Activity Rate
Divide the total cost in each pool by the total units of that cost driver.
Step 5: Assign Costs to Products
Multiply each product’s actual usage of a cost driver by the activity rate for that pool. Add all pools together to get the total overhead assigned to that product.
Activity-Based Costing Formula
The core formula is:
Activity Rate = Total Cost Pool / Total Cost Drivers
Then:
Overhead Assigned to Product = Activity Rate x Product’s Usage of That Driver
Example: A factory spends $10,000 per year on machine setups and runs 500 setups total.
- Activity Rate = $10,000 / 500 = $20 per setup
- If Product A requires 80 setups: 80 x $20 = $1,600 in setup costs assigned to Product A
If the manufacturing overhead costs are caused by a number of activities such as setup, procurement, handling, and production, then using the activity based costing method of determining costs will give a result that is closer to the true costs.
ABC vs Traditional Costing
ABC systems trace overhead costs to specific activities and cost objects, resulting in greater accuracy. Traditional systems simply allocate costs using a limited number of allocation bases like machine hours or direct labor, which can distort product costs.
ABC systems track numerous cost drivers and activities, which makes them more complex to design and maintain.
| Feature | Traditional Costing | Activity Based Costing |
|---|---|---|
| Cost allocation basis | Single driver (e.g., labor hours) | Multiple drivers (setups, inspections, orders) |
| Accuracy | Lower, can over or under cost products | Higher, reflects actual resource use |
| Complexity | Simple and fast | More detailed and time intensive |
| Best for | Small firms, few products | Complex operations, diverse products |
| Cost to implement | Low | Higher |
| Pricing decisions | Less reliable | More reliable |
A comparison of the overhead per unit calculated using the ABC and traditional methods often shows very different results. Under traditional costing, a product with high direct labor dollars gets allocated more overhead costs than a product with low direct labor dollars.
The number of orders, setups, or tests the product actually uses does not impact the allocation of overhead costs when direct labor dollars are used to allocate overhead.
Real Life Examples
Manufacturing: Two Products, One Plant
Consider two products manufactured by the same company. Product 124 is a low volume item that requires special engineering, additional testing, and many machine setups because it is ordered in small quantities. Product 366 is a high volume product that runs continuously and requires little attention and no special activities.
Under traditional costing, both products might receive similar overhead allocations because they share the same production floor. Under ABC, Product 124 would correctly receive far more overhead because it actually consumes more engineering time, testing, and setup resources. This gives managers accurate cost data to price each product correctly and evaluate profitability.
Healthcare: Hospital Patient Costs
A hospital might identify specific activities whose general costs must be shared among patients. Each activity rate is estimated based on the activity’s budgeted overhead cost for the year divided by the number of occurrences expected during the year. For each patient stay, the number of times each activity occurs is multiplied by the overhead rate for that activity.
UPMC overcame these technological challenges by using a system that provides actual supply and labor costs, assigns costs to multiple activities within a department, and uses a flexible cost engine to deliver easily accessible, reliable, and actionable data.
Unlike traditional costing methods that evenly distribute overhead costs across all hospital services, ABC assigns costs based on the actual activities involved in patient care. This approach reveals the true cost of each service line, helping hospitals make smarter decisions about pricing, resource allocation, and profitability.
Banking and Financial Services
Banks use ABC to figure out which customers and products are actually profitable. Processing a simple savings account requires very different activities than managing a complex commercial loan. ABC helps assign the real cost of each service and reveals which customer segments are worth pursuing.
Advantages of Activity Based Costing
a) More Accurate Product Costs
The main advantage of activity based costing is that it allows for more precise cost allocation by recognizing that different products or services may consume resources at different rates.
This is especially important when a company produces both high volume and low volume products, since the low volume product typically demands far more overhead per unit.
b) Better Understanding of Cost Behavior
ABC reveals which activities actually drive costs. Managers can then focus on reducing or eliminating non-value-adding activities rather than simply cutting headcounts or budgets across the board.
c) Stronger Pricing Decisions
When you know the true cost of a product, you can price it more accurately. This matters most in competitive markets where thin margins can turn a profitable product into a money loser if costs are miscalculated.
d) Overhead Tracing Beyond the Factory Floor
ABC traces costs to areas including customers, departments, and processes, not just products. This helps businesses allocate budgets where they are truly needed rather than spreading resources evenly.
e) Supports Better Budgeting
ABC methods essentially convert the so-called indirect costs of traditional costing methods into direct costs. This visibility supports activity based budgeting, where future resource needs are projected based on planned activity levels rather than historical spending.
f) Service Industry Benefits
ABC combines concepts of process mapping from engineering with costing models of accounting, and has been successfully expanded to industries such as hospitality and technology. Users of ABC often credit the accounting method with the identification of opportunities to improve efficiency and productivity.
Disadvantages of Activity Based Costing
a) Time Consuming to Set Up
Implementing ABC requires manually identifying every activity, grouping them into cost pools, selecting appropriate cost drivers, and calculating rates. For a mid sized manufacturing company, this can take months and may require a dedicated team or an outside consultant.
b) Higher Implementation Cost
ABC systems are more accurate than traditional costing systems because they provide a more precise breakdown of indirect costs. However, ABC systems are more complex and more costly to implement. The leap from traditional costing to activity based costing is difficult.
c) Difficult Cost Driver Selection
Choosing the right cost driver for each activity is not always straightforward. A poor choice can produce inaccurate results, defeating the purpose of the method.
d) Less Useful for Smaller Businesses
Manufacturing businesses with high overhead costs use activity based costing to get a clearer picture of where money is going. Traditional costing is simpler but less specific than activity based costing. You might consider going with traditional costing if you only make a few products.
e) Data Maintenance is Ongoing
Activity cost rates need to be updated regularly. The overhead for machine setups or customer service changes year over year, and stale rates lead to stale cost data.
f) Does Not Follow GAAP
ABC is primarily an internal management tool. It is not required or recognized under Generally Accepted Accounting Principles (GAAP) for external financial reporting. Companies still need traditional costing for financial statements.
Who Should Use Activity Based Costing?
ABC works best for organizations that:
- Produce multiple products or services with different complexity levels
- Have high overhead costs that are difficult to trace directly to products
- Need accurate pricing data to remain competitive
- Want to identify waste and inefficiency in their operations
- Operate in manufacturing, healthcare, banking, logistics, or hospitality
Smaller businesses with simple, uniform products and low overhead may find that traditional costing is sufficient and far less expensive to manage.
Frequently Asked Questions
What is activity based costing in simple terms?
ABC is a way of figuring out the true cost of making a product by tracking the specific activities required, rather than splitting all overhead costs evenly across every product.
What is the difference between ABC and traditional costing?
Traditional costing uses a single factor like labor hours to spread overhead costs. ABC uses multiple cost drivers that match each type of overhead to the activity that actually causes it, producing more accurate results.
What industries use activity based costing the most?
Manufacturing is the most common, but ABC is also widely used in healthcare, banking, hospitality, and logistics. Any organization with high overhead and diverse services can benefit from it.
Is activity based costing required by GAAP?
No. ABC is an internal management accounting tool. It is not required by GAAP for external financial statements, though it can be used alongside GAAP compliant reporting.
What is a cost driver in ABC?
A cost driver is the factor that causes a cost to change. For machine setup costs, the cost driver might be the number of setups per period. For customer service costs, it might be the number of customer calls handled.
What are the five steps of activity based costing?
The five steps are: (1) identify activities, (2) group them into cost pools, (3) identify cost drivers for each pool, (4) calculate the activity rate, and (5) assign costs to products based on their actual use of each activity.
Can small businesses use activity based costing?
They can, but it may not be worth the effort. Small businesses with simple operations and few products usually get sufficient accuracy from traditional costing. ABC adds the most value when overhead is high and products vary significantly in complexity.
What is time driven activity based costing?
Time driven ABC (TDABC) is a simplified version developed by Robert Kaplan and Steven Anderson that uses time as the primary cost driver. It is easier to maintain and update than standard ABC.
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MBA- Finance Specialization
I am Smirti Bam, an enthusiastic edu blogger with a passion for sharing insights into the dynamic world of business and management through this website.
I hold a MBA degree from Presidential Business School, Kathmandu, and a BBA degree with a specialization in Finance from Apex College,
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