"How to File an Affidavit of Support
You, the sponsor, should complete Form I-864 when your relative has been scheduled for an immigrant visa interview with a consular officer overseas or when your relative is about to submit an application for adjustment to permanent resident status with the USCIS or with an Immigration Court in the United States. If you have a joint sponsor, they must also complete Form I-864. If you are using the income of other household members to qualify, then each household member who is accepting legal responsibility for supporting your relative must complete a separate Form I-864A, Contract Between Sponsor and Household Member."