(5)Where an asset forming part of a block of qualifying assets begins to be used for purposes other than the tonnage tax business, an appropriate portion of the written down value allocable to such asset shall be reduced from the written down value of that block and shall be added to the block of other assets.Explanation. - For the purposes of this sub-section, appropriate portion of the written down value allocable to the asset, which begins to be used for purposes other than the tonnage tax business, shall be an amount which bears the same proportion to the written down value of the block of qualifying assets as on the first day of the previous year as the book written down value of the asset beginning to be used for purposes other than tonnage tax business bears to the book written down value of all the assets forming the block of qualifying asset.
