a) Santo has three product lines: P1, P2, and P3. Since its inception, the company has been using a single direct labour cost percentage to assign overhead costs to products. Despite P3 being a relatively new product line, it is attracting additional business. However, increasing overhead costs have resulted in loss-making in recent times. P2 particularly has been a significant product line since its inception. However, it has lost considerable market share due to an increase in overhead cost in recent times and a consequent increase in price per unit. Management is, therefore, convinced that the costing system needs some review. A team led by the management accountant was put together to develop an improved system of costing based on activities. The team spent several weeks collecting data for the different activities and products.

Below is data on Santo’s three product lines and overhead costs for the current accounting period:

P1 P2 P3
Production volume (units) 7,500 12,500 4,000
Selling price per unit (GH¢) 47 80 68
Material cost per unit (GH¢) 18 25 16
Direct labour cost per unit (GH¢) 4 8 6.4
Materials movements (in total) 4 25 50
Machine hours per unit 0.5 0.5 0.2
Set-ups (in total) 1 5 10
The proportion of engineering work 30% 20% 50%
Orders packed (in total) 1 7 22

Activities overhead cost:

  • Machine maintenance and depreciation: GH¢390,000
  • Material receiving and handling: GH¢150,000
  • Engineering: GH¢100,000
  • Packing: GH¢60,000
  • Set-up labour: GH¢18,688
  • Total: GH¢718,688

Required: Identify for each overhead activity, an appropriate cost driver from the information supplied, and then calculate the product unit costs using a system that assigns overheads based on the use of activities. (10 marks)

Unit Costs Calculation for Santo’s Product Lines

Overhead Costs P1 (GH¢) P2 (GH¢) P3 (GH¢)
Direct materials 18.00 25.00 16.00
Direct labour 4.00 8.00 6.40
Prime cost 22.00 33.00 22.40
Receiving/materials handling 1.01 3.80 23.73
Maintenance and depreciation 18.06 18.06 7.22
Set-up labour 0.16 0.47 2.92
Engineering 4.00 1.60 12.50
Packing 0.27 1.12 11.00
Sub-total overhead costs 23.50 25.05 57.37
Total unit cost 45.50 58.05 79.77

ABC Workings:

  1. Receiving and handling materials cost
    Total cost = GH¢150,000
    Cost driver = Number of materials movements
    Number of materials movements = 4 + 25 + 50 = 79 movements
    Cost per material movement = GH¢150,000 / 79 = GH¢1,898.73

    • Cost per unit of P1 = (GH¢1,898.73 × 4) / 7,500 = GH¢1.01
    • Cost per unit of P2 = (GH¢1,898.73 × 25) / 12,500 = GH¢3.80
    • Cost per unit of P3 = (GH¢1,898.73 × 50) / 4,000 = GH¢23.73
  2. Maintenance and depreciation cost
    Total cost = GH¢390,000
    Cost driver = Number of machine hours
    Number of machine hours = (0.5 × 7,500) + (0.5 × 12,500) + (0.2 × 4,000) = 10,800
    Cost per machine hour = GH¢390,000 / 10,800 = GH¢36.11

    • Cost per unit of P1 = GH¢36.11 × 0.5 = GH¢18.06
    • Cost per unit of P2 = GH¢36.11 × 0.5 = GH¢18.06
    • Cost per unit of P3 = GH¢36.11 × 0.2 = GH¢7.22
  3. Set-up labour cost
    Total cost = GH¢18,688
    Cost driver = Number of set-ups
    Number of set-ups = 1 + 5 + 10 = 16
    Cost per set-up = GH¢18,688 / 16 = GH¢1,168

    • Cost per unit of P1 = (GH¢1,168 × 1) / 7,500 = GH¢0.16
    • Cost per unit of P2 = (GH¢1,168 × 5) / 12,500 = GH¢0.47
    • Cost per unit of P3 = (GH¢1,168 × 10) / 4,000 = GH¢2.92
  4. Engineering cost
    Total cost = GH¢100,000
    Cost driver = Proportion of engineering work

    • Cost per unit of P1 = (GH¢100,000 × 30%) / 7,500 = GH¢4.00
    • Cost per unit of P2 = (GH¢100,000 × 20%) / 12,500 = GH¢1.60
    • Cost per unit of P3 = (GH¢100,000 × 50%) / 4,000 = GH¢12.50
  5. Packing cost
    Total cost = GH¢60,000
    Cost driver = Number of orders packed
    Number of orders packed = 1 + 7 + 22 = 30
    Cost per order = GH¢60,000 / 30 = GH¢2,000

    • Cost per unit of P1 = (GH¢2,000 × 1) / 7,500 = GH¢0.27
    • Cost per unit of P2 = (GH¢2,000 × 7) / 12,500 = GH¢1.12
    • Cost per unit of P3 = (GH¢2,000 × 22) / 4,000 = GH¢11.00