(4)Where for any assessment year, the interest expenditure is not wholly deducted against income under the head "Profits and gains of business or profession", so much of the interest expenditure as has not been so deducted, shall be carried forward to the following assessment year or assessment years, and it shall be allowed as a deduction against the profits and gains, if any, of any business or profession carried on by it and assessable for that assessment year to the extent of maximum allowable interest expenditure in accordance with sub-section (2):Provided that no interest expenditure shall be carried forward under this sub-section for more than eight assessment years immediately succeeding the assessment year for which the excess interest expenditure was first computed.
