Capital gains deferral for compulsory acquisition when replacement land or building is acquired or constructed, altering tax charge and cost basis. Where compulsory acquisition of land or building forming part of an industrial undertaking occurs and the assessee acquires or constructs a replacement asset within three years, the capital gain is adjusted against the cost of the replacement asset: any excess of the capital gain over the replacement cost is charged as income and the replacement asset's cost is treated as nil for computing any capital gain on its disposal within the prescribed period; if the capital gain is equal to or less than the replacement cost, the gain is not charged and the replacement asset's cost is reduced by the amount of the gain.