Understanding block-wise WDV computation, additions, sales, and when a block ceases to exist
Depreciation is one of the most useful deductions available to a business, and once you understand how the block of assets system works, calculating it becomes refreshingly straightforward. Unlike the Companies Act, which tracks depreciation asset-by-asset, the Income Tax Act uses a simpler, more efficient block approach. This guide walks through the concept step by step, with worked examples, so you can apply it confidently to any client’s fixed asset schedule.
1. The Block of Assets Concept
Section 2(11) of the Income Tax Act defines a ‘block of assets’ as a group of assets falling within the same class — tangible assets such as buildings, machinery, plant, or furniture, or intangible assets such as patents, copyrights, trademarks, licences, and franchises — for which the same rate of depreciation is prescribed.
In practice, this means you do not depreciate each machine or vehicle individually. Instead, every asset eligible for the same rate is pooled into one block, and depreciation under Section 32 is computed on the written down value (WDV) of the block as a whole, not on individual assets. This has a few important consequences:
- Once an asset enters a block, it loses its individual identity for depreciation purposes.
- You do not need to track the WDV of each individual asset year after year — only the block’s combined WDV.
- Gain or loss on sale of an individual asset is generally not computed separately; it flows through the block (see Section 4).
Good practice: maintain a fixed asset register with individual asset detail for internal control and audit purposes, even though the tax computation itself only needs block-level figures.
2. Rates and Classification of Blocks
The Income Tax Rules (Appendix I) prescribe the rate applicable to each class of asset. A few commonly used rates are illustrated below — always verify the current rate against the latest Rules before filing, as rates and classifications are occasionally revised.
| Block | Illustrative Assets | Rate of Depreciation |
| Building (residential) | Staff quarters, residential buildings | 5% |
| Building (non-residential) | Factory, office premises | 10% |
| Furniture and fittings | Furniture, fixtures | 10% |
| Plant and machinery (general) | General plant and machinery | 15% |
| Motor vehicles (general use) | Cars, vans not used in a hiring business | 15% |
| Computers, including software | Computers, laptops, software | 40% |
| Intangible assets | Patents, trademarks, licences, franchises | 25% |
3. Computing Depreciation: The Basic WDV Formula
Depreciation for the year is computed on the WDV of the block as at the beginning of the year, adjusted for additions and deletions during the year:
Depreciation = Rate × [Opening WDV of block + Cost of assets acquired during the year − Sale consideration/moneys receivable for assets sold, discarded, or destroyed during the year]
This adjusted figure — opening WDV plus additions minus deletions — is what the Act calls the WDV of the block as on the last day of the previous year, and it is this figure to which the rate is applied.
4. Additions During the Year — the 180-Day Rule
When a new asset is added to a block during the year, the depreciation allowed depends on how long it was used in that year:
- Asset put to use for 180 days or more in the year of acquisition: full year’s depreciation at the normal rate.
- Asset put to use for less than 180 days in the year of acquisition: depreciation restricted to 50% of the normal rate, for that year only.
The 180-day test looks only at the date the asset is put to use, not the date of purchase or invoicing. From the following year onward, the asset merges fully into the block and the 180-day restriction no longer applies — the full rate is charged on the entire block WDV, addition included.
5. Sale, Discarding, or Destruction of an Asset — Effect on the Block
When an asset within a block is sold, discarded, demolished, or destroyed during the year, the moneys payable in respect of it (sale price, insurance/scrap value, compensation, etc.) are simply deducted from the block’s WDV before applying the rate — there is no separate gain or loss computed on that individual asset, so long as the block continues to exist and has a positive balance after the deduction.
This is one of the most useful features of the block system for a growing business: selling an old machine at a profit or loss over its individual book value does not, by itself, trigger a taxable event. The sale proceeds simply reduce the pool on which future depreciation is calculated.
6. Illustrative Example — Additions and Deletions in the Same Block
Consider a Plant and Machinery block (rate 15%) for a manufacturing client for FY 2025-26:
| Particulars | Amount (₹) |
| Opening WDV as on 1 April 2025 | 50,00,000 |
| Add: New machine purchased and used from 10 June 2025 (used > 180 days) | 12,00,000 |
| Add: New machine purchased and used from 5 January 2026 (used < 180 days) | 6,00,000 |
| Less: Sale proceeds of an old machine sold in August 2025 | (4,00,000) |
| WDV before depreciation | 64,00,000 |
Because the 180-day rule applies asset-by-asset only in the year of addition (not to the block as a whole), depreciation is split into two components for the current year:
| Component | Base (₹) | Rate Applied | Depreciation (₹) |
| Opening WDV + additions used ≥ 180 days, less deletions | 50,00,000 + 12,00,000 − 4,00,000 = 58,00,000 | 15% | 8,70,000 |
| Addition used < 180 days | 6,00,000 | 7.5% (half rate) | 45,000 |
| Total depreciation for FY 2025-26 | 9,15,000 |
Closing WDV carried forward to FY 2026-27 = ₹64,00,000 − ₹9,15,000 = ₹54,85,000. From next year, this entire figure is treated as a single opening WDV, and the half-rate addition loses its special treatment entirely.
7. When the Block Ceases to Exist — the ‘Block Deleted’ Concept
A block can come to an end in two distinct situations, and it is important to tell them apart correctly:
(a) All assets in the block are sold, but sale proceeds are less than or equal to the WDV
If every asset in the block is transferred during the year and the block itself ceases to have any remaining WDV or any assets, but the sale proceeds are less than the opening WDV plus additions, the shortfall is allowed as a short-term capital loss under Section 50, and no depreciation is allowed for that year (since no asset remains in the block on the last day of the year).
(b) Sale proceeds exceed the WDV of the block (block extinguished with a surplus)
If the aggregate sale consideration of all assets in the block exceeds the opening WDV plus cost of additions during the year, the excess is treated as short-term capital gain under Section 50 — even if the individual assets had been held for several years and would otherwise qualify as long-term capital assets. This is the well-known exception where long-held block assets can still generate short-term gains purely because of how the block mechanism works.
Key distinguishing test for ‘block deleted’: the block ceases to exist only when (i) no asset remains physically in the block at the end of the year, AND (ii) the block’s WDV would otherwise be nil or negative. If even one asset remains in the block, normal block depreciation continues on the reduced WDV — there is no block deletion and no Section 50 gain, however large the deduction for sale proceeds is.
8. Illustrative Example — Block Extinguished During the Year
A furniture block (rate 10%) has an opening WDV of ₹3,00,000 on 1 April 2025. All items in the block are sold during the year for ₹4,50,000, and no new furniture is purchased. No asset remains in the block at year end.
| Particulars | Amount (₹) |
| Opening WDV as on 1 April 2025 | 3,00,000 |
| Add: Additions during the year | Nil |
| Less: Sale consideration of all assets in the block | (4,50,000) |
| Resulting figure | (1,50,000) |
Since the block no longer contains any asset and the sale proceeds exceed the WDV, the entire ₹1,50,000 is short-term capital gain under Section 50 in FY 2025-26. No depreciation is claimed on this block for the year, and the block itself ceases to exist — there is nothing to carry forward.
Had the sale proceeds instead been, say, ₹2,00,000 (less than the opening WDV of ₹3,00,000), the block would still cease to exist, but the shortfall of ₹1,00,000 would be a short-term capital loss under Section 50, again with no depreciation for the year.
9. Disclosure Requirements
Accurate block-wise disclosure matters both for the return of income and for the tax audit report, and reviewers frequently check these figures first:
- Form 3CD (Clause 18): requires block-wise particulars of depreciation — opening WDV, additions (split between assets used for 180 days or more and less than 180 days, with the date of acquisition/put to use), deductions on account of sale/discard/destruction, depreciation allowable, and closing WDV.
- Additions should be supported by asset-wise detail (description, date put to use, cost) even though only the block total is reported, so that the 180-day split is defensible on scrutiny.
- Deletions should be supported by sale invoices, insurance claim settlements, or scrap sale vouchers, and the actual moneys receivable — not the book value — is what reduces the block.
- Where a block is fully extinguished during the year, the Section 50 short-term capital gain or loss should be separately reported in the capital gains schedule of the return (Schedule CG), in addition to being reflected in the depreciation schedule as a nil closing balance.
- Depreciation schedule in the return (ITR / computation) should reconcile block-wise: opening WDV + additions − deletions = WDV before depreciation; less depreciation = closing WDV — carried forward consistently year on year.
10. Practical Takeaways
- Think in blocks, not individual assets — this is what makes the mechanism efficient once you get comfortable with it.
- Always test the 180-day rule at the point of addition, and remember it only affects the year of addition.
- Sale proceeds reduce the block WDV directly; a separate capital gain arises only when the block itself is fully extinguished.
- When a block is extinguished, check the direction of the shortfall/surplus carefully — surplus is short-term capital gain, shortfall is short-term capital loss, both under Section 50, regardless of the original holding period of the assets.
- Keep supporting asset-wise workings even though the return only needs block totals — this makes Clause 18 disclosures and scrutiny responses far easier to prepare.
With the block system, depreciation moves from being a asset-by-asset tracking exercise to a clean, formula-driven calculation. Once the additions, deletions, and 180-day treatment are correctly captured, the rest of the computation — including the Section 50 outcome when a block winds down — follows naturally.