Depreciation Formula: Practical Guide for Business Success

Depreciation allocates a tangible asset's cost over its useful life, reflecting its gradual loss in value due to use, wear or obsolescence. It ensures expenses match the income they generate, keeping financial statements accurate. Depreciation also supports tax calculations, legal compliance in India and a realistic view of asset usage. 

How to calculate depreciation?

Depreciation is calculated according to different rules depending on the regulatory framework. Here are the three key rules you must know:

• Companies Act, 2013

Under the Companies Act, 2013 (Schedule II), companies calculate depreciation using the useful lives specified therein. Entities may choose either the Straight Line Method (SLM) or the Written Down Value (WDV) method, provided they maintain consistency. Useful life defines the asset's operational period, and residual value is generally capped at 5% of the original cost unless justified otherwise.

• Income Tax Act, 1961

Under the Income Tax Act, 1961 (Section 32), depreciation is computed using a block of assets system. Assets are grouped into categories, each with a prescribed rate. These groups include plants, machinery, furniture and other assets. The Written Down Value (WDV) method is mandatory for tax purposes.

• Accounting Standard

Component accounting is applied under Accounting Standard (AS) 10 for non-Ind AS entities, and Ind AS 16 for companies following Ind AS. Significant parts of an asset with different useful lives receive separate depreciation treatment. This approach improves the accuracy of financial reporting for complex assets, such as machinery or infrastructure units.

Straight line vs written down value method

Here is a comparison between the two depreciation methods:

Comparing these methods helps businesses decide whether to spread depreciation evenly or accelerate it in the early years.

Application of the straight line and the written-down value formulas

To calculate depreciation correctly, you need accurate inputs. The key factors are the asset's cost, its residual value and its useful life. Any inconsistency among these inputs can lead to incorrect reporting.

• Straight line method (SLM)

The depreciation formula is: (Cost of Asset − Residual Value) ÷ Useful Life

The Straight Line Method allocates depreciation evenly over an asset's lifespan, reflecting a steady economic benefit. Assets such as office furniture, buildings and fixtures typically use this method.

Example: If an asset costs ₹1,00,000, has a residual value of ₹10,000 and a useful life of 9 years, the annual depreciation will be ₹10,000.

• Written down value (WDV) method

The depreciation formula is: Opening Book Value × Depreciation Rate

The Written Down Value method results in higher depreciation in the initial years. It is suitable for assets that lose value faster during early use, such as machinery or technology-based equipment.

Example: If an asset costs ₹1,00,000 and the depreciation rate is 15%, depreciation for Year 1 will be ₹15,000 and for Year 2 it will be ₹12,750 (calculated on the reduced value).

Important tax rule: "Put to use" condition

Under Section 32 of the Income-tax Act, depreciation is allowed only when an asset is actually put to use for business or professional purposes. Even trial use qualifies.

A key rule is the 180-day condition:

• If the asset is used for 180 days or more during the financial year, full depreciation is allowed.
• If the asset is used for less than 180 days, only 50% of the prescribed depreciation is allowed in that year.

Depreciation is computed on a block of assets, and in certain cases, such as additional depreciation, the remaining 50% may be claimed in subsequent years.

Additional key provisions:

• Additional depreciation under Section 32(1)(iia) is available for certain manufacturing businesses.
• Depreciation is not allowed on land.
• Depreciation of goodwill is not allowed as per recent judicial rulings.
• Pro rata depreciation applies to assets added during the year.

Conclusion

To make depreciation work effectively for your business, focus on choosing the right method, maintaining accurate asset details and correctly applying tax rules, such as the 180-day condition. Review your asset register regularly to avoid errors and remain compliant. Using accounting software like TallyPrime can help you manage depreciation efficiently, keep financial reports accurate and organised and support better decision-making.