The eligible business were the only source of income, during the previous year relevant to the initial assessment year and every subsequent assessment years. When the assessee exercises the option, the only losses of the years beginning from initial assessment year alone are to be brought forward and no losses of earlier years which were already set off against the income of the assessee. Looking forward to a period of ten years from the initial assessment is contemplated. It does not allow the Revenue to look backward and find out if there is any loss of earlier years and bring forward notionally even though the same were set off against other income of the assessee and the set off against the current income of the eligible business. Once the set off is taken place in earlier year against the other income of the assessee, the Revenue cannot rework the set off amount and bring it notionally. A fiction created in subsection does not contemplates to bring set off amount notionally. The fiction is created only for the limited purpose and the same cannot be extended beyond the purpose for which it is created