Explanation.—For the removal of doubts, it is hereby declared that any income-tax authority, being an authority higher in rank, may, if so directed by the Board, exercise the powers and perform the functions of the income-tax authority lower in rank and any such direction issued by the Board shall be deemed to be a direction issued under sub-section (1).

(2) The directions of the Board under sub-section (1) may authorise any other income-tax authority to issue orders in writing for the exercise of the powers and performance of the functions by all or any of the other income-tax authorities who are subordinate to it.

(3) In issuing the directions or orders referred to in sub-sections (1) and (2), the Board or other income-tax authority authorised by it may have regard to any one or more of the following criteria, namely :—

(a)  territorial area;

(b)  persons or classes of persons;

(c)  incomes or classes of income; and

(d)  cases or classes of cases.

(4) Without prejudice to the provisions of sub-sections (1) and (2), the Board may, by general or special order, and subject to such conditions, restrictions or limitations as may be specified therein,—

(a) authorise any Principal Director General or Director General or Principal Director or Director to perform such functions of any other income-tax authority as may be assigned to him by the Board;

(b) empower the Principal Director General or Director General or Principal Chief Commissioner or Chief Commissioner or Principal Commissioner or Commissioner to issue orders in writing that the powers and functions conferred on, or as the case may be, assigned to, the Assessing Officer by or under this Act in respect of any specified area or persons or classes of persons or incomes or classes of income or cases or classes of cases, shall be exercised or performed by an Additional Commissioner or an Additional Director or a Joint Commissioner or a Joint Director, and, where any order is made under this clause, references in any other provision of this Act, or in any rule made thereunder to the Assessing Officer shall be deemed to be references to such Additional Commissioner or Additional Director or Joint Commissioner or Joint Director by whom the powers and functions are to be exercised or performed under such order, and any provision of this Act requiring approval or sanction of the Joint Commissioner shall not apply.

(5) The directions and orders referred to in sub-sections (1) and (2) may, wherever considered necessary or appropriate for the proper management of the work, require two or more Assessing Officers (whether or not of the same class) to exercise and perform, concurrently, the powers and functions in respect of any area or persons or classes of persons or incomes or classes of income or cases or classes of cases; and, where such powers and functions are exercised and performed concurrently by the Assessing Officers of different classes, any authority lower in rank amongst them shall exercise the powers and perform the functions as any higher authority amongst them may direct, and, further, references in any other provision of this Act or in any rule made thereunder to the Assessing Officer shall be deemed to be references to such higher authority and any provision of this Act requiring approval or sanction of any such authority shall not apply.

(6) Notwithstanding anything contained in any direction or order issued under this section, or in section 124, the Board may, by notification in the Official Gazette, direct that for the purpose of furnishing of the return of income or the doing of any other act or thing under this Act or any rule made thereunder by any person or class of persons, the income-tax authority exercising and performing the powers and functions in relation to the said person or class of persons shall be such authority as may be specified in the notification.