Form I-864 (Affidavit of Support Under Section 213A of the Act) is used to prove that the immigrant has enough financial support to live and stay in the USA without becoming a public charge.
This form acts as a contract between the sponsor (the person who is providing the financial support for the intending immigrant) and the US Government, which makes it the sponsor's obligation to provide support for the beneficiary until such time that the contract ends. Special attention should be paid to the responsibilities of the sponsor.
For example, if the sponsor is the beneficiary's spouse and the couple get divorced, the sponsor is still bound by the contract within form I-864.
To become a sponsor for an intending immigrant, the sponsor must provide evidence that their income is at least 125% of the current Federal Poverty Level. If the sponsor is in the US Armed Forces, and the intending immigrant is the sponsor's spouse or child, the income only needs to be 100% of the Federal Poverty Level.
If the sponsor is not able to meet the required level of income, a joint sponsor can be used in conjunction with the primary sponsor's income. A joint sponsor can be any USC, US National, Lawful Permanent Resident who is at least 18 years old and domiciled within the US, it's territories or possessions, and who is willing to be liable, along with the primary sponsor, for the intending immigrant. The joint sponsor will be bound by the same contract that the primary sponsor is.
There may be no more than two joint sponsors.