Form I-864, Affidavit of Support under Section 213A of the INA, is a contract an individual signs agreeing to use their financial resources to support the intending immigrant named on the affidavit. The individual who signs the affidavit of support becomes the sponsor once the intending immigrant becomes a lawful permanent resident. The sponsor is usually the petitioner who filed an immigrant petition on behalf of the intending immigrant.
An affidavit of support is a legally enforceable contract, and the sponsor’s responsibility usually lasts until the family member or other individual either becomes a U.S. citizen, or is credited with 40 quarters of work (usually 10 years).
The law concerning the affidavit of support is found in Sections 212(a)(4) and 213A of the Immigration and Nationality Act (INA). The provisions are codified in Title 8 of the Code of Federal Regulations (CFR) at 8 CFR 213a.
For more information visit the USCIS page.