Tribunal office hours set for working days, with the President retaining power to alter timings by order. The administrative offices of the Goods and Services Tax Appellate Tribunal are to remain open on all working days from 9:30 a.m. to 6:00 p.m., subject to any order made by the President. The provision regulates the office hours of the Tribunal's administrative establishment and preserves the President's authority to alter those hours by order.