USCIS provides Information on Filing Form I-539
USCIS reminds applicants to include all required evidence when submitting Form I-539, Application to Extend/Change Nonimmigrant Status. The required initial evidence for nonimmigrants requesting an extension of stay is included in the instructions for Form I-539. Initial evidence is required for all applications regardless of whether they are electronically filed in USCIS ELIS or mailed to USCIS.