O-1 extensions are initiated through departmental request to the Office of Global Services. Extensions can be submitted to the U.S. Citizenship and Immigration Services as early as one year in advance of the begin date of the extension. The Office of Global Services monitors extensions but it is a good idea for you to remind your department administrator as well. An employee for whom an O-1 extension petition is filed with USCIS in a timely manner, i.e., before the end date of the current petition, may continue to work for 240 days while the case is pending.