Component Accounting Under AS 10 and Schedule II: How to Depreciate Significant Parts of an Asset

Component accounting becomes important when one large asset is made up of significant parts that wear out or are replaced at different times. A company may buy a production line, aircraft, building system or heavy machine as one commercial package, but that does not always mean it should be depreciated as one undivided block.

For entities applying Accounting Standards, ICAI's AS 10, Property, Plant and Equipment is the primary accounting reference. For companies, Schedule II also matters. The official Schedule II amendment notification specifically addresses significant parts with different useful lives, while the India Code Companies Act page provides the statutory landing page and Schedule II access.

What component accounting means

Component accounting means identifying significant parts of an item of property, plant and equipment and depreciating those parts separately when required. AS 10 states that each part whose cost is significant in relation to the total cost of the item should be depreciated separately, with the amount initially recognised for the asset allocated to its significant parts.

This does not mean every small part needs its own asset code. Materiality and judgement still matter. AS 10 does not prescribe a universal percentage for deciding whether a component is significant. A finance team should use a documented policy considering cost, useful life, replacement pattern and the likely effect on depreciation.

How AS 10 and Schedule II fit together

AS 10 gives the accounting principle. Paragraphs 45 to 49 require significant-cost parts to be considered separately for depreciation, while allowing significant parts with the same useful life and depreciation method to be grouped when determining the depreciation charge.

Schedule II adds the company-law useful-life framework. Its amendment states that the useful life in Part C is for the asset as a whole and that, where a part is significant to total cost and has a different useful life from the remaining asset, the useful life of that significant part should be determined separately. The notification made this requirement mandatory for financial statements for financial years commencing on or after 1 April 2015.

Schedule II also says useful life should not ordinarily differ from Part C and residual value should not ordinarily exceed five per cent of original cost. If a company uses a different useful life or residual value, the difference should be disclosed and justified with technical advice.

A practical seven-step workflow

1. Identify the complete asset. Confirm what has been capitalised and the total qualifying cost.
2. Map major parts. Use specifications, engineering documents, bills of materials, vendor break-ups, maintenance schedules and replacement history.
3. Identify significant components. Focus on parts whose cost is material and whose useful life, consumption pattern or replacement cycle makes separate depreciation meaningful.
4. Allocate cost reliably. Use invoice values where available. For bundled prices, support the split through vendor quotations, engineering estimates, relative replacement values or another rational basis.
5. Set useful life and method. Determine the expected life of each significant component and use a depreciation method reflecting its consumption pattern. Parts with the same life and method may be grouped.
6. Update the fixed asset register. Maintain component-level cost, accumulated depreciation, useful life, residual value, method and replacement history.
7. Review annually. AS 10 requires useful life and residual value to be reviewed at least at each financial year-end, and the depreciation method also needs review for significant changes in consumption pattern.

Worked illustration

Assume a manufacturing line is capitalised at Rs. 100 lakh. Engineering information identifies three significant components: the main structure at Rs. 70 lakh, a turbine at Rs. 20 lakh and a control system at Rs. 10 lakh. For illustration only, assume useful lives of 20 years, 10 years and 5 years respectively, zero residual values and straight-line depreciation.

• Main structure: Rs. 70 lakh divided by 20 years = Rs. 3.50 lakh per year.
• Turbine: Rs. 20 lakh divided by 10 years = Rs. 2.00 lakh per year.
• Control system: Rs. 10 lakh divided by 5 years = Rs. 2.00 lakh per year.

Total annual depreciation under those assumptions is Rs. 7.50 lakh. If the entire Rs. 100 lakh were depreciated mechanically over 20 years, the annual charge would be Rs. 5 lakh and the shorter-lived components would be depreciated too slowly. The assumed lives are purely illustrative; actual lives must be determined from the facts and the applicable Schedule II and accounting-standard requirements.

What happens when a component is replaced?

Replacement accounting is a major reason to maintain component records properly. AS 10 permits the cost of a replacement part to be recognised in the carrying amount when the recognition criteria are met. At the same time, the carrying amount of the part being replaced should be derecognised.

This prevents the balance sheet from carrying both the old component and the new one. If the carrying amount of the replaced part cannot be determined directly, AS 10 allows the replacement cost to be used as an indication of what the replaced part cost when originally acquired or constructed, subject to appropriate judgement.

Common mistakes to avoid

• Using one life for a complex asset by default. One invoice does not prove there is only one depreciable component.
• Using an arbitrary significance percentage as if it were law. A policy threshold can help administration, but AS 10 does not prescribe one universal percentage.
• Ignoring engineering evidence. Major components often need technical input for useful-life estimates.
• Capitalising a replacement but leaving the old component in the register. This can overstate carrying amount.
• Confusing book and tax depreciation. Component accounting is a financial-reporting exercise; tax depreciation follows its own statutory framework.

Year-end checklist

• Review major asset additions for significant components.
• Check cost allocations and technical support.
• Review useful lives, residual values and depreciation methods.
• Verify that replaced components have been derecognised.
• Reconcile component depreciation to the fixed asset register and general ledger.
• Document any Schedule II deviation and the supporting technical basis.

Practical takeaway

Component accounting is not about creating more asset codes. Its purpose is to make depreciation and replacement accounting reflect how a complex asset is actually consumed. Identify significant parts, allocate cost on a supportable basis, assign appropriate lives and methods, derecognise replaced components and keep the fixed asset register capable of explaining the accounting. For current technical wording, refer directly to AS 10 on the ICAI platform and the official Schedule II amendment notification.