Management Accounting 101: Activity-Based Costing and Activity-Based Management - Time-Driven Activity-Based, Costing TDABC Practical Capacity Time Equations

What This Is

Time-Driven Activity-Based Costing (TDABC) is a management accounting technique that assigns costs to products or services based on the actual time consumed by activities. This approach helps managers make informed decisions by accurately allocating costs and identifying areas for improvement. For example, Toyota uses TDABC to optimize production costs and improve efficiency in its manufacturing processes.

Key Frameworks & Metrics

• Time-Driven Activity-Based Costing (TDABC): assigns costs to products or services based on the actual time consumed by activities, rather than traditional volume-based methods.
• Activity-Based Costing (ABC): a framework for assigning costs to products or services based on the activities they consume, with a focus on time and effort.
• Time Equation: Time = Activity Volume × Activity Rate, where time is the output, activity volume is the number of times an activity is performed, and activity rate is the time required to perform one unit of the activity.
• Capacity Utilization: measures the percentage of available capacity used by a product or service, calculated as Capacity Utilization = Actual Time / Available Time.
• Efficiency Ratio: measures the efficiency of a process or activity, calculated as Efficiency Ratio = Actual Time / Standard Time.
• Product Cost: the total cost of producing a product, including direct materials, direct labor, and overhead costs.
• Contribution Margin: the difference between revenue and variable costs, calculated as Contribution Margin = Revenue - Variable Costs.
• Break-Even Point (units): the number of units that must be sold to cover all costs, calculated as Break-Even Point (units) = Fixed Costs / Contribution Margin per Unit.
• Economic Value Added (EVA): a measure of a company's true economic profit, calculated as EVA = NOPAT - (Capital Invested × WACC).

Step-by-Step Process

1. Identify Activities: list all the activities performed in a process or department, including both value-added and non-value-added activities.
2. Assign Time: assign the actual time consumed by each activity, using time studies or other methods to determine the time required for each activity.
3. Calculate Activity Rates: calculate the activity rate for each activity, which is the time required to perform one unit of the activity.
4. Assign Costs: assign costs to each activity based on the activity rate and the time consumed by the activity.
5. Calculate Product Costs: calculate the product cost by summing the costs of all the activities consumed by the product.
6. Analyze Results: analyze the results to identify areas for improvement and opportunities to reduce costs.

Common Mistakes

• Mistake: Treating all costs as relevant, when in fact some costs may be irrelevant or fixed.
• Correction: Only consider costs that are variable and relevant to the decision at hand.
• Mistake: Ignoring qualitative factors in make-or-buy decisions.
• Correction: Consider both quantitative and qualitative factors when making make-or-buy decisions.
• Mistake: Using ROI alone without considering residual income or EVA.
• Correction: Use a combination of ROI, residual income, and EVA to evaluate investment opportunities.

Decision-Making Tips

• Tip: When faced with a make-or-buy decision, always isolate avoidable costs and consider strategic, not just quantitative, factors.
• Tip: Use TDABC to optimize production costs and improve efficiency in manufacturing processes.
• Tip: Consider both short-term and long-term costs when making investment decisions.

Quick Practice Scenario

A company uses TDABC to calculate the product cost of a low-volume product that consumes 10 setups and 5 design changes. If the activity rate for setup is $100 per hour and the activity rate for design change is $50 per hour, and the product requires 2 hours of setup and 1 hour of design change, what is the product cost?

Answer: $250 (2 hours x $100 per hour + 1 hour x $50 per hour)

Explanation: The product cost is calculated by summing the costs of all the activities consumed by the product, which in this case includes setup and design change activities.

Last-Minute Cram Sheet

• 'Fixed costs' are only fixed in the short run within a relevant range – outside that range, they can change.
• Time-Driven Activity-Based Costing (TDABC) assigns costs to products or services based on the actual time consumed by activities.
• Activity-Based Costing (ABC) is a framework for assigning costs to products or services based on the activities they consume.
• Time = Activity Volume × Activity Rate.
• Capacity Utilization = Actual Time / Available Time.
• Efficiency Ratio = Actual Time / Standard Time.
• Product Cost = Direct Materials + Direct Labor + Overhead Costs.
• Contribution Margin = Revenue - Variable Costs.
• Break-Even Point (units) = Fixed Costs / Contribution Margin per Unit.
• EVA = NOPAT - (Capital Invested × WACC).
• ROI alone is not sufficient to evaluate investment opportunities – consider residual income and EVA as well.