What is activity-based costing?

Activity-based costing (ABC) is a method that assigns overhead costs to specific activities that drive them, then allocates those costs to products or services based on consumption. For professional service firms, ABC provides more accurate project and client costing than traditional methods by tracing overhead to the activities that actually cause the costs, such as proposal development, project management, or quality review.

Key characteristics

• Assigns overhead to activities that cause costs

• Allocates based on actual activity consumption

• More accurate than volume-based allocation

• Identifies true cost drivers

• Requires activity tracking and analysis

• Enables better pricing and profitability decisions

Why it matters for professional service firms

Traditional overhead allocation methods (such as the percentage-of-direct-labor method) can significantly distort project profitability. A complex project that consumes significant proposal and management time may appear profitable as a simple project when overhead is spread evenly. Activity-based costing reveals the truth: complex projects consume more resources and should be priced accordingly. Professional service firms benefit from ABC insights even without full ABC implementation by understanding which activities drive overhead costs.

Real-world example

Amanda's consulting firm allocated overhead as 50% of direct labor. All projects appeared similarly profitable. ABC analysis tracked actual activity consumption: proposal development, project management, quality review, billing, and collection. Results: Project Type A consumed 3x average proposal time and 2x management time; actual overhead was 85% of direct labor. Project Type B consumed minimal overhead; the actual rate was 25%. Pricing adjusted accordingly: Type A prices increased 15% to reflect true cost, and Type B pricing became more competitive. Overall profitability improved as pricing aligned with actual resource consumption.