I-864 Affidavit of Support Form along with past 3 year U.S tax returns (or transcripts) and any other financial documents required.
[web]http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=b70f8875d714d010VgnVCM10000048f3d6a1RCRD&vgnextchannel=db029c7755cb9010VgnVCM10000045f3d6a1RCRD[/web]
