Job order costing: accounting for spoilage

Accounting for normal and abnormal spoilage

In a job order costing system, spoilage, also known as waste or defective units, can occur during production. It is essential to classify spoilage correctly, as this affects both inventory valuation and the reporting of expenses in the income statement. Spoilage is typically categorized as either normal or abnormal, based on its nature and cause.

Normal spoilage

Normal spoilage refers to waste that is expected or unavoidable under efficient operating conditions. It is considered part of the regular cost of manufacturing and is typically absorbed by good units produced.

• If the spoilage is job-specific, the cost is assigned to the job itself.
• If the spoilage is common to all jobs, it is treated as part of manufacturing overhead and allocated accordingly.

Example for normal spoilage:

A furniture manufacturer expects 2 defective tables per 100 due to wood warping. If 2 units are spoiled during Job #212 (which produced 100 units), the spoilage is considered normal and is included in the cost of Job #212. NO journal entry is required to be done since the costs of the normal spoilage flows into the inventory or COGS along with the good units.

Abnormal spoilage

Abnormal spoilage arises from unexpected and avoidable causes, such as operator errors, equipment failure, or substandard inputs. Since these losses are not considered part of efficient operations, they are treated as period costs and expensed immediately on the income statement.

• Abnormal spoilage is not included in inventory valuation.
• It is recorded as a separate expense line under operating costs or “Loss from Abnormal Spoilage.” \

To compute the cost assigned to abnormal spoilage:

$$\text{Abnormal Spoilage Cost}=(\frac{\text{Total Cost}}{\text{Total Units}–\text{Normal Loss Units}})\times \text{Abnormal Spoilage Units}$$

Where:

• Total Cost = combined cost of direct materials, direct labor, and applied overhead
• Normal Loss Units = expected spoilage under efficient conditions
• Abnormal Spoilage Units = excess spoilage beyond normal expectations

Example for abnormal spoilage:

A batch of 1,000 units has a total cost of $12,000. The company expects normal spoilage of 2% (20 units), but 35 units were spoiled. This results in 15 units of abnormal spoilage.

$$\begin{array}{rl}\text{Abnormal Spoilage per Unit}& =(\frac{\text{Total Cost}}{\text{Total Units}–\text{Normal Loss Units}})\\ & =(\frac{12,000}{1,000–20})\\ & =(\frac{12,000}{980})\\ & =12.24\end{array}$$

$$\begin{array}{rl}\text{Cost of Abnormal Spoilage}& =\text{Abnormal Spoilage per Unit}\times \text{Abnormal Spoilage Units}\\ & =12.24\times 15\\ & =183.6\end{array}$$

Abnormal Spoilage Cost is $183.6 which should be charged as a period expense.

Assume the abnormal spoilage cost of $183.6 (as computed earlier) occurred during Job #412 due to a machine malfunction.

Transaction	Debit	Credit	Explanation
Record abnormal spoilage	Loss from Abnormal Spoilage: $183.6	Work-in-Process – Job #412: $183.6	To recognize the cost of abnormal spoilage as a period expense

The debit goes to an income statement account, often titled “Loss from Abnormal Spoilage” or similar while the credit removes the cost of spoiled units from WIP to avoid overstating inventory.

Benefits and limitations of job order costing

Understanding the strengths and constraints of the job order costing system helps organizations determine whether it is the appropriate costing approach for their operations. This section summarizes the most important benefits and limitations.

Benefits of job order costing

• Direct materials and labor are traced to individual jobs, giving precise cost visibility at the job level.
• Ideal for industries where each job or batch is unique (e.g., construction, consulting, legal, and custom manufacturing).
• By identifying the actual cost of each job, businesses can price accurately and evaluate the profitability of specific contracts or clients.
• Departments or project teams can be held responsible for job-specific cost overruns or savings.
• Particularly for service firms, job costing allows for detailed billing and transparent explanations of charges.

Limitations of job order costing

• Requires detailed tracking and documentation of costs for each job, increasing administrative workload.
• Overhead is applied using predetermined rates, which may lead to under- or overapplied overhead, distorting true job costs.
• In industries with homogeneous, repetitive output, process costing is typically more efficient.
• Especially for smaller organizations or firms with limited resources, the system may be burdensome.
• If overhead drivers are poorly chosen, overhead costs may not reflect true resource consumption, leading to inaccurate cost assignments. :::