Proof of Residency in Fairfax County. You will be required to show proof of residency during the registration process.Proof of residency: A deed, lease agreement, or resident manager's letter and signed attestation indicating the current residence. There are five stages for application submission. 1. If you want to sponsor someone for a family-based green card, you need to provide proof of a U.S. domicile in your Affidavit of Support (Form I-864). Please submit proof of domicile. PLEASE READ BEFORE FILLING OUT ON-LINE FORMS. Adobe Reader XI is required to be able to save a filled out copy of your filing for your records.