Understanding Depreciation and Depletion

Depreciation, depletion, and amortization are accounting methods used to allocate the cost of an asset over its useful life. These methods recognize that assets lose value over time due to wear and tear, obsolescence, or consumption.

• Depreciation: Applied to tangible fixed assets like buildings, machinery, furniture, etc., which lose value due to usage, time, or technological advancements.
• Depletion: Applied to natural resources like mines, oil wells, quarries, and timberlands. This method accounts for the exhaustion of the resource as it is extracted or used.
• Amortization: Applied to intangible assets like patents, copyrights, software, and trademarks, representing the systematic writing off of their cost over their legal or useful life.

Depletion Method Explained

The depletion method is specifically designed for natural resources that are consumed or exhausted. It is based on the units of resource extracted or produced during a period. The cost of the asset (the natural resource property) is allocated based on the proportion of the total estimated resource extracted in a period.

The formula for calculating depletion cost per unit is typically:

\(\text{Depletion Cost Per Unit} = \frac{\text{Cost of Resource Property} - \text{Salvage Value}}{\text{Estimated Total Units of Resource}}\)

The total depletion expense for a period is then calculated as:

\(\text{Depletion Expense} = \text{Depletion Cost Per Unit} \times \text{Units Extracted During the Period}\)

Assets Using Depletion Method

The depletion method is used for assets that are finite natural resources, such as:

• Mines (coal, gold, iron ore, etc.)
• Oil and gas wells
• Quarries (stone, gravel, sand)
• Timberlands (forests where trees are harvested)

Analyzing the Given Assets for Depletion Method

Let's look at the assets listed in the options:

• Plant and Machinery: These are tangible fixed assets that are used in production or operations. Their value decreases due to wear and tear and obsolescence. Depreciation methods like Straight-Line Method, Diminishing Balance Method, etc., are used for Plant and Machinery.
• Building and Furniture: These are also tangible fixed assets. Buildings lose value over time due to aging and wear, while furniture wears out with use. They are subject to depreciation using methods appropriate for tangible assets.
• Software: This is an intangible asset. Its cost is typically spread over its useful life or legal life using the amortization method.

None of the assets listed (Plant and Machinery, Building and Furniture, Software) are natural resources that are physically extracted or consumed in the way minerals, oil, or timber are. Therefore, the depletion method is not appropriate for charging depreciation on these assets.

Conclusion on Depletion Method Application

Based on the nature of the assets listed in the options and the definition of the depletion method, the depletion method is not used for Plant and Machinery, Building and Furniture, or Software. The depletion method is reserved for natural resource properties.

Therefore, for charging depreciation (more accurately, cost allocation) on which of the listed assets the depletion method is adopted, the answer is none of them.