Your department will invite you to complete Applicant Sections in an E-3 Application. Please look for an email from your department with instructions. 

The E-3 category provides for entry on a non-permanent basis into the US for up to 24 months at a time

E-3 status may be extended either by traveling outside the US and applying for an E-3 visa stamp at a US Consulate/Embassy or, in the case of an alien already in the U.S., by applying to the Vermont Service Center for a change of status or extension of status on Form I-129. Supporting documents to be submitted with an E-3 application include:  1) proof that the alien is a national of the Commonwealth of Australia; 2) a letter from the U.S. employer describing the specialty occupation to be engaged in, the anticipated length of stay, and the arrangements for remuneration; 3) evidence the alien meets the educational requirement for the specialty occupation, which must be a U.S. bachelor’s degree or higher (or its equivalent) in the specific specialty; 4) evidence the alien meets any other licensure or occupational requirements; and 5) a certified Labor Condition Application (LCA) from the Department of Labor.

An E-3 Employee may continue her/his employment for up to 240 days if USCIS receives the petition prior to the end date listed on the E-3’s I-94.   The 240-day period commences on the day following the expiration of the previous USCIS approval. If the petition were to be denied within that 240-day period, the employment authorization would end on that day.