Inventory Systems (Grade 12 NSC Matric Accounting): Revision Notes
Inventory Systems
When businesses sell goods, they need an effective way to track and manage their stock. Understanding the different inventory systems available helps businesses choose the most suitable method for recording and controlling their inventory levels.
What are inventories?
Inventories (also called trading stock) refer to goods that businesses purchase with the intention of reselling them to customers at a profit. These items represent a significant asset for trading businesses, and they must always be recorded in the accounting books at their original cost price, not at their selling price.
Critical Principle: Trading stock must always be recorded at cost price, never at selling price. This fundamental accounting principle ensures accurate financial reporting and prevents overstatement of assets.
Types of inventory systems
Businesses can choose between two main inventory systems to manage their stock effectively. Each system has distinct characteristics that make it suitable for different types of businesses and situations.
The choice between inventory systems is a strategic decision that affects how businesses track stock, calculate profits, and maintain control over their assets. Consider your business size, transaction volume, and control requirements when making this choice.
Perpetual inventory system
The perpetual system provides continuous, real-time tracking of inventory levels. This system treats inventory as a balance sheet account called "trading stock," which is classified as an asset account.
How the perpetual system works
Under this system, businesses maintain detailed records that are updated every time stock moves in or out of the business. When goods are purchased, the trading stock account receives a debit entry reflecting the cost price, which increases the asset value. Conversely, when goods are sold, the trading stock account gets a credit entry for the cost price, reducing the asset value.
The system also requires businesses to calculate and record the cost of sales immediately whenever goods are sold. Any additional costs related to purchasing stock, such as carriage on purchases (transport costs), are also debited to the trading stock account.
Benefits of the perpetual system
The perpetual system offers superior internal control over inventory because it provides managers with up-to-date information about stock levels at any given moment. This real-time visibility helps prevent stockouts, reduces the risk of theft, and enables better decision-making regarding purchasing and sales strategies.
Key Advantage: The perpetual system's real-time tracking capability makes it invaluable for preventing stockouts and detecting theft immediately, providing businesses with the highest level of inventory control.
When to use the perpetual system
Businesses typically choose the perpetual system when they need tight control over their inventory and have the resources to maintain detailed records. This system works well for businesses with valuable stock items or those operating in competitive markets where accurate stock information is crucial.
Periodic inventory system
The periodic system takes a different approach by tracking inventory at specific intervals rather than continuously. This system is more suitable for businesses where calculating cost of sales after every transaction would be impractical or too costly.
How the periodic system works
In the periodic system, stock purchases are recorded in a nominal account called "purchases", which is classified as an expense account. Additional costs associated with purchasing, such as carriage on purchases, are recorded separately in their own nominal expense accounts rather than being added to the stock value.
Since this system doesn't track inventory continuously, the cost of sales can only be determined at specific periods (usually monthly, quarterly, or annually) using a special calculation.
Cost of sales calculation
The periodic system uses the following formula to determine cost of sales:
This formula ensures that all costs related to the goods sold during the period are properly accounted for in determining the business's profitability.
Worked Example: Cost of Sales Calculation
A business has the following information for the month:
- Opening stock: R5,000
- Purchases: R15,000
- Carriage on purchases: R500
- Closing stock: R3,500
Calculation: Cost of sales = R5,000 + R15,000 + R500 - R3,500 = R17,000
This means the business sold $17,000 worth of goods (at cost price) during the month.
When to use the periodic system
Businesses often choose the periodic system when it's not practical or cost-effective to calculate cost of sales after every transaction. This might be the case for businesses dealing with low-value items, high transaction volumes, or those with limited accounting resources.
Key differences between systems
| Aspect | Perpetual System | Periodic System |
|---|---|---|
| Tracking frequency | Continuous, real-time | At specific intervals |
| Stock account type | Balance sheet (asset account) | Nominal (expense account) |
| Cost of sales calculation | After each sale | Periodically using formula |
| Internal control | Excellent | Limited |
| Administrative burden | Higher | Lower |
| Suitability | Valuable stock, need for control | High volume, low-value items |
Choosing the right system
The choice between perpetual and periodic systems depends on several factors including the nature of the business, the value of inventory, available resources, and the level of control required. Many modern businesses use computerised systems that make perpetual inventory tracking more feasible and cost-effective than in the past.
Modern technology has made perpetual inventory systems more accessible to smaller businesses. Cloud-based inventory management software can automate much of the record-keeping, reducing the administrative burden traditionally associated with perpetual systems.
Key Points to Remember:
- Perpetual system provides continuous tracking and better control but requires more administrative work
- Periodic system is simpler to maintain but offers limited real-time inventory information
- Trading stock is always recorded at cost price, never at selling price
- Cost of sales formula: Opening stock + Purchases + Additional costs - Closing stock = Cost of sales
- Choose the system that best matches your business needs and available resources