The extent to which residents of the United States who are not U.S. citizens should be eligible for federally funded public aid has been a contentious issue since the 1990s. This issue meets at the intersection of two major policy areas: immigration policy and welfare policy. Over the past 20 years, Congress has enacted significant changes in both areas. Congress has also exercised oversight of revisions made by the 1996 welfare reform law (the Personal Responsibility and Work Opportunity Reconciliation Act, P.L. 104-193 ) concerning the rules governing noncitizen eligibility for public assistance, and of legislation covering programs with major restrictions on noncitizen eligibility (e.g., Medicaid). This report covers noncitizen eligibility in the four major federal means-tested benefit programs: the Supplemental Nutrition Assistance Program (SNAP, formerly food stamps), the Supplemental Security Income (SSI) program, Temporary Assistance for Needy Families (TANF) cash assistance, and Medicaid. It is organized into three main parts: an overview of existing eligibility law for the four programs and the policies that preceded the 1996 act; an overview of related immigrant policies affecting eligibility (specifically, the treatment of sponsored aliens); and a summary of the eligibility rules for aliens residing in the United States illegally. Appendices elaborate on the specifics of current eligibility rules for the four major programs. Among other things, Title IV of the Personal Responsibility and Work Opportunity Reconciliation Act of 1996 (PRWORA, P.L. 104-193 ) established comprehensive restrictions on the eligibility of noncitizens for means-tested public assistance—with significant exceptions for those with a substantial U.S. work history or military connection. For legal permanent residents (LPRs) who were resident as of enactment of the law (August 22, 1996), the act generally had barred eligibility (SNAP and SSI) or had allowed it at state option (Medicaid and TANF). For SNAP and SSI benefits, LPRs entering after August 22, 1996 (new entrants) also had been denied eligibility. Refugees and asylees, however, were allowed eligibility the first five years after entry/grant of status, then became ineligible after five years (unless they became citizens or qualified under another status). Nonimmigrants and unauthorized aliens were barred from almost all federal programs. Under current law, lawful permanent residents' eligibility for the major federal means-tested benefit programs depends on their immigration status; whether they arrived (or were on a program's rolls) before August 22, 1996 (the enactment date of P.L. 104-193 ); their work history and military connection; their length of legal residence; and how states have exercised their options to allow program participation by noncitizens. Following significant changes made by the 1997, 1998, and 2002 amendments, the basic rules are as follows: Refugees and asylees are eligible for food stamps/SNAP. Refugees and asylees are eligible for SSI benefits and Medicaid for seven years after arrival and are eligible for TANF for five years. After this term, they generally are ineligible for SSI, but may be eligible, at state option, for Medicaid and TANF. LPRs with a substantial work history—generally 10 years (40 quarters) of work documented by Social Security or other employment records—or a military connection (active duty military personnel, veterans, and their families) are eligible for the full range of programs. LPRs are not eligible for SSI during the first five years even if they had 40 credits of earnings (e.g., as a temporary worker prior to receiving LPR status). LPRs receiving SSI as of August 22, 1996, continue to be eligible for SSI. Noncitizen SSI recipients are eligible for (and required to be covered under) Medicaid. Disabled LPRs who were legal residents as of August 22, 1996, are eligible for SSI. Disabled LPRs are eligible for SNAP. LPRs who were elderly (65+) and legal residents as of August 22, 1996, are eligible for SNAP. LPRs who have been legal residents for five years or are children (under 18) are eligible for SNAP. LPRs entering after August 22, 1996, are barred from TANF and Medicaid for five years, after which their coverage becomes a state option. States have the option to cover LPRs who are children or who are pregnant during the first five years. Nonimmigrants and unauthorized aliens are ineligible for SNAP, SSI, and TANF. They are also ineligible for Medicaid with the exception of Medicaid for emergency conditions. States have the option to cover nonimmigrant and unauthorized aliens who are pregnant or who are children, and can meet the definition of "lawfully residing" in the United States. Appendix A lays out these rules in more detail, including special rules that apply to several limited noncitizen categories: certain "cross-border" American Indians, Hmong/Highland Laotians, parolees and conditional entrants, and cases of abuse. Citizens of the Freely Associated States (FAS, which are the Marshall Islands, Micronesia, and Palau) are afforded certain immigration-related benefits that enable them to travel freely to and from the United States in a legal status akin to nonimmigrants. Citizens of the FAS who come from the Republic of the Marshall Islands (RMI) and the Federated States of Micronesia (FSM) are permitted to live, study, and work in the United States in accordance with the Compact of Free Association Amendments Act of 2003 (Compact, P.L. 108-188 ). FAS citizens are not considered LPRs under the Immigration and Nationality Act (INA), but they are permitted to acquire LPR status if otherwise eligible. While in the United States, FAS citizens from the RMI and FSM are able to document their legal status with their RMI or FSM passports and the I-94 arrival/departure card issued to them when they enter the United States. FAS citizens from the Republic of Palau do not benefit from the immigration provisions in the Compact that permit those from the RMI or FSM to seek employment, go to school, or establish a residence. Citizens of the Republic of Palau only need to present an appropriate travel document, such as a valid passport or a certified birth certificate, to enter the United States. Under current law, FAS citizens are not eligible for federal public benefits (except emergency services and programs expressly listed, such as Medicaid for emergency medical care or Federal Emergency Management Agency disaster services). Prior to 1996, FAS citizens residing in the United States were able to obtain federal assistance because they were considered "permanently residing under color of law" (PRUCOL), which is an eligibility standard that is not defined in statute. Historically, PRUCOL has been used to provide a benefit to certain foreign nationals who the government knows are present in the United States, but whom it has no plans to deport or remove. When Title IV of P.L. 104-193 established comprehensive limitations and requirements on the eligibility of all noncitizens for means-tested public assistance, it effectively ended access to federal benefits for foreign nationals who had been considered PRUCOL. As a consequence, citizens of the FAS residing in the United States are barred from receiving most federal public benefits. For many years, LPRs have been considered (deemed) to have a portion of their immigration sponsors' income and resources available to them for the purpose of determining whether the LPR meets the financial eligibility requirement of the means-tested benefit program. The current "deeming rules" (primarily set out in the 1996 welfare reform act) are designed to make it more difficult for sponsored aliens to meet financial tests for benefits—even if they pass the "categorical" eligibility test by being in an eligible class of noncitizen. In other words, the sponsor's and LPR's income and resources combined are used to determine whether the LPR meets the financial eligibility threshold for participation in the program, decreasing the likelihood that the LPR will qualify for the benefit. Deeming rules apply to aliens who enter after December 19, 1997, and who apply for TANF, Medicaid, SSI, or SNAP. Under these rules, all of the income and resources of a sponsor (and a sponsor's spouse) may be deemed available to the sponsored applicant for assistance until the noncitizen becomes naturalized or has 40 quarters of Social Security covered earnings. Previous law contained specific deeming requirements only for SSI, food stamps, and AFDC (TANF's predecessor); only a portion of a sponsor's income and resources was deemed to the sponsored applicant; and deeming lasted for three years after entry (with a brief five-year rule for SSI). Since it is Section 213A of the Immigration and Nationality Act (INA) that makes the affidavits of support legally binding, some policymakers use "213A" as shorthand to identify who is covered by the deeming rules. The Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA, Division C of P.L. 104-208 ) altered the obligations of persons who sponsor LPRs in the United States. When IIRIRA made an affidavit of support a legally binding contract, it also directed the Attorney General (now the Secretary of Homeland Security) to include "appropriate information" regarding affidavits of support in the Systematic Alien Verification for Entitlements (SAVE) system. While Congress did not specify exactly what information was to be included in the SAVE system, it did require the Attorney General to establish an automated record of the sponsors' social security numbers.