Depreciation Calculator
Companies Act and Income Tax Act, with the schedule year by year.
Choose the basis. Companies Act works from useful life and residual value; the Income Tax Act works from block rates.
Two regimes, two answers
Book depreciation follows the useful life in Schedule II. Tax depreciation follows block rates on the written down value of the block. They legitimately differ, and the gap is a timing difference that feeds deferred tax.
Blocks, not assets
Under the Income Tax Act, depreciation is computed on the block as a whole. Individual assets lose their identity once they enter a block, which is why a sale reduces the block rather than producing a gain, until the block itself is exhausted.
The 180-day rule
An asset put to use for fewer than 180 days in the year of acquisition gets half the normal rate. It is about the date the asset was put to use, not the date of purchase or of payment.
Deriving the WDV rate
Schedule II gives useful life, not a WDV rate. The rate is derived as one minus the useful-life root of the ratio of residual value to cost, which is what this calculator does rather than asking you to look it up.