use of Form I-20 Establishing legality of status and stay The Form I-20 serves as evidence of the legality of the student's current presence in the United States. Note that a valid visa is not necessary for being in lawful student status; a valid visa is only needed when entering or re-entering the United States. Documentation of student status for United States government purposes The Form I-20 may be used to demonstrate student status when applying for United States government documents and benefits such as Individual Taxpayer Identification Number (ITIN) and Social Security Number. It is also required to demonstrate authorization to work for students on Curricular Practical Training. Travel and travel signatures Whenever the student re-enters the United States after traveling, the student must have all of these at the time of arrival at the port of entry: A valid passport (valid for at least six more months) A valid F or M visa A valid I-20 (i.e., an I-20 whose program end date has not yet arrived) A travel signature on the I-20 (page 3) from the DSO that is at most one year old (six months in the case of students currently on post-completion Optional Practical Training) Since travel signatures are valid for only a year, students need to periodically get updated travel signatures on their I-20 from their international student office. The purpose of this requirement is to avoid cases where people who are no longer enrolled as students at an institution keep using an outdated Form I-20 to get in. In particular, when adding a new travel signature to the OPT, it is the responsibility of the international student office to make sure that the student is still enrolled at the institution. In case the Form I-20 runs out of space for travel signatures, the international office may print out a new Form I-20 for the student. In the special case of automatic visa revalidation, whereby the student returns to the United States after a trip to Canada, Mexico, or a nearby island for at most 30 days, it is not necessary to have a valid visa at the time of re-entry. However, it is still necessary to have a valid Form I-20 and a travel signature. Changes to Form I-20 In general, whenever there are changes to the information in Form I-20, a new Form I-20 is issued. The student is advised to keep