Management Accounting 101: Activity-Based Costing and Activity-Based Management - ABC vs. Traditional, Costing Under/Over-Costing Cross-Subsidisation

What This Is

Activity-Based Costing (ABC) vs Traditional Costing: This is a fundamental concept in management accounting that helps managers understand the true costs of products or services. Traditional costing methods, such as absorption costing, can lead to under-costing or over-costing, while ABC provides a more accurate picture of costs. For example, Toyota uses ABC to track costs associated with each model, allowing them to make informed decisions about production and pricing.

Key Frameworks & Metrics

• Activity-Based Costing (ABC): A method that assigns costs to products or services based on the activities they require. Practical use: helps managers understand the true costs of products or services and make informed decisions.
• Absorption Costing: A traditional method that assigns fixed and variable costs to products or services based on their production volume. Practical use: simple to implement, but can lead to under-costing or over-costing.
• Under-Costing: When the cost of a product or service is lower than its actual cost. Practical use: can lead to incorrect pricing and profitability decisions.
• Over-Costing: When the cost of a product or service is higher than its actual cost. Practical use: can lead to incorrect pricing and profitability decisions.
• Cross-Subsidization: When costs are transferred from one product or service to another. Practical use: can lead to incorrect pricing and profitability decisions.
• Contribution Margin (CM) = Sales - Variable Costs: Measures the amount of money available to cover fixed costs and generate profit. Practical use: helps managers understand the profitability of products or services.
• Break-Even Point (units) = Fixed Costs / Contribution Margin per Unit: Tells you how many units must be sold to cover all costs. Practical use: helps managers understand the minimum sales required to break even.
• Economic Value Added (EVA) = NOPAT - (Capital Invested × WACC): Measures true economic profit after charging for the cost of capital. Practical use: helps managers understand the true profitability of investments.

Step-by-Step Process

1. Identify Activities: Determine the activities required to produce a product or service.
2. Assign Costs: Assign costs to activities based on their usage.
3. Assign Activity Costs: Assign activity costs to products or services based on their usage.
4. Calculate Product Costs: Calculate the total cost of a product or service using ABC.
5. Compare to Traditional Costing: Compare ABC product costs to traditional costing methods.
6. Make Informed Decisions: Use ABC product costs to make informed decisions about pricing, production, and resource allocation.

Common Mistakes

• Mistake: Treating all costs as relevant when using ABC.
• Correction: Only include costs that are directly related to the product or service being analyzed.
• Mistake: Ignoring qualitative factors in make-or-buy decisions.
• Correction: Consider strategic, not just quantitative, factors when making make-or-buy decisions.
• Mistake: Using ROI alone without considering residual income or EVA.
• Correction: Use a combination of metrics to understand the true profitability of investments.

Decision-Making Tips

• When faced with a make-or-buy decision, always isolate avoidable costs and consider strategic, not just quantitative, factors.
• When using ABC, consider the impact of activity costs on product costs.
• When evaluating investments, use a combination of metrics, including ROI, residual income, and EVA.

Quick Practice Scenario

Scenario: A division rejects a project because its ROI would drop from 18% to 17%. By how much would residual income change if the project cost is $1M and the required rate of return is 12%?

Answer: Residual income would increase by $80,000.

Explanation: Residual income = (Project income - Required return on investment) = ($1.2M - $1.08M) = $120,000.

Last-Minute Cram Sheet

• ABC = Activity-Based Costing: A method that assigns costs to products or services based on the activities they require.
• Absorption Costing: A traditional method that assigns fixed and variable costs to products or services based on their production volume.
• Under-Costing: When the cost of a product or service is lower than its actual cost.
• Over-Costing: When the cost of a product or service is higher than its actual cost.
• Cross-Subsidization: When costs are transferred from one product or service to another.
• Contribution Margin (CM) = Sales - Variable Costs: Measures the amount of money available to cover fixed costs and generate profit.
• Break-Even Point (units) = Fixed Costs / Contribution Margin per Unit: Tells you how many units must be sold to cover all costs.
• Economic Value Added (EVA) = NOPAT - (Capital Invested × WACC): Measures true economic profit after charging for the cost of capital.
• 'Fixed costs' are only fixed in the short run within a relevant range – outside that range, they can change.
• ABC is more accurate than traditional costing methods, but requires more data and analysis.
• ROI alone is not enough to evaluate investments – consider residual income and EVA as well.