I am an H-1B visa holder and my employer is filing to extend my H-1B for an additional three years. Do I have to file a separate extension for my wife and childs H4 visa?
Yes, you must file a Form I-539 application. Typically, you file the Form I-539 application at the same time as the H-1B extension petition. In appropriate circumstances, you can also file the Form I-539 application after your H-1B extension is filed. In this case, you include a copy of the I-797 Receipt Notice from your H-1B extension petition.