Any fiduciary who conducts or is liquidating the business or is selling the assets of any company subject to tax under § 12-587 shall be subject to requirements related to filing returns and to payment of taxes imposed under said section in the same manner and to the same extent as if the business were being conducted or liquidated or assets sold by agents or officers of such company. The return of any fiduciary who has been appointed during a taxable quarter or following such quarter but on or before the last day upon which a return may be filed for such quarter without penalty, shall include complete information with respect to that part of such quarter during which the company conducted the business as well as that part of such quarter in which such fiduciary was acting and taxes shall be paid by such fiduciary for both parts of such quarter.