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. 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.
You are required to provide your U.S. federal income tax return for the most recent tax year as well as proof of current employment. If you were not required to file a tax return in any of these years you must provide an explanation. Failure to provide the tax return or evidence establishing that you were not required to file will delay action on your relative's application for permanent residence. If this information is not provided, this will result in denial of an immigrant visa or adjustment of status.
When you have completed the affidavit of support, compiled the necessary documentation, and had the affidavit notarized in the United States or before a U.S. consular or immigration officer, you should provide this packet of information to your relative to submit with his or her application. If you are given specific instructions to file your affidavit of support directly with the National Visa Center, you should follow those instructions.
Income Requirements
You also must meet certain income requirements (whether you are a sponsor, a joint sponsor, or a substitute sponsor). You must show that your household income is equal to or higher than 125% of the U.S. poverty level for your household size. (Your household size includes you, your dependents, any relatives living with you, and the immigrants you are sponsoring.)
If you, the sponsor, are on active duty in the Armed Forces of the United States, and the immigrant you are sponsoring is your spouse or child, your income only needs to equal 100% of the U.S. poverty level for your household size.
If you cannot meet the minimum income requirements using your earned income, you have various options:
You may add the cash value of your assets. This includes money in savings accounts, stocks, bonds, and property. To determine the amount of assets required to qualify, subtract your household income from the minimum income requirement (125% of the poverty level for your family size). You must prove the cash value of your assets is worth five times this difference (the amount left over).
Exceptions:
If the person being sponsored is a spouse, or son/daughter (who is 18 years or older) of a U.S. citizen: The minimum cash value of assets must be three times the difference between the sponsor’s household income and 125% of the federal poverty guide line for the household.
If the person being sponsored is an orphan coming to the United States for adoption: The adoptive parents’ assets need to equal or exceed the difference between the household income and 125% of the federal poverty line for the household size.
You may count the income and assets of members of your household who are related to you by birth, marriage, or adoption. To use their income you must have listed them as dependents on your most recent federal tax return or they must have lived with you for the last 6 months. They must also complete a Form I-864A, Contract between Sponsor and Household Member. If the relative you are sponsoring meets these criteria you may include the value of their income and assets, but the immigrant does not need to complete Form I-864A unless he or she has accompanying family members.
Responsibilities as a Sponsor
When you sign the affidavit of support, you accept legal responsibility for financially supporting the sponsored immigrant(s) generally until they become U.S. citizen or can be credited with 40 quarters of work. Your obligation also ends if you or the individual sponsored dies or if the individual sponsored ceases to be a permanent resident and departs the United States.
Note: Divorce does NOT end the sponsorship obligation.
If the individual you sponsored receives any "means-tested public benefits," you are responsible for repaying the cost of those benefits to the agency that provided them. If you do not repay the debt, the agency can sue you in court to get the money owed. Any joint sponsors or household members whose income is used to meet the minimum income requirements are also legally responsible for financially supporting the sponsored immigrant.
Change of Address
If you change your address after you become a sponsor, you are required by law to notify the USCIS within 30 days by filing Form I-865, Sponsor's Notice of Change of Address. If you fail to notify the USCIS of your change of address, you may be fined.
http://www.travel.state.gov/visa/immigrants/info/info_3197.html