Activity-based Costing (ABC) vs Traditional Costing

See Also:
Activity Based Costing
Standard Costing System
Cost Driver
Value Chain
Implementing Activity Based Costing
Absorption vs Variable Costing
Activity Based Management
Process Costing
Overhead
Job Costing

Activity Based Costing Costing vs Traditional Costing

In the field of accounting, activity-based costing and traditional costing are two different methods for allocating indirect (overhead) costs to products.
Both methods estimate overhead costs related to production and then assign these costs to products based on a cost-driver rate. The differences are in the accuracy and complexity of the two methods. Traditional costing is more simplistic and less accurate than ABC, and typically assigns overhead costs to products based on an arbitrary average rate. ABC is more complex and more accurate than traditional costing. This method first assigns indirect costs to activities and then assigns the costs to products based on the products’ usage of the activities.

Traditional Costing Method

Traditional costing systems apply indirect costs to products based on a predetermined overhead rate. Unlike ABC, traditional costing systems treat overhead costs as a single pool of indirect costs. Traditional costing is optimal when indirect costs are low compared to direct costs. There are several steps in the traditional costing process, including the following:
1. Identify indirect costs.
2. Estimate indirect costs for the appropriate period (month, quarter, year).
3. Choose a cost-driver with a causal link to the cost (labor hours, machine hours).
4. Estimate an amount for the cost-driver for the appropriate period (labor hours per quarter, etc.).
5. Compute the predetermined overhead rate (see below).
6. Apply overhead to products using the predetermined overhead rate.

Predetermined Overhead Rate Calculation

Use the following formula to calculate predetermined overhead rate:

Predetermined Overhead Rate = Estimated Overhead Costs / Estimated Cost-Driver Amount

For example:

$30/labor hr = $360,000 indirect costs / 12,000 hours of direct labor

Activity-Based Costing Benefits

Activity based costing systems are more accurate than traditional costing systems. This is 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.

Traditional Costing Advantages and Disadvantages

Traditional costing systems are simpler and easier to implement than ABC systems. However, traditional costing systems are not as accurate as ABC systems. Traditional costing systems can also result in significant under-costing and over-costing.
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