Since the inception of the Social Security program in 1935, the Social Security number and, to a lesser extent, the Social Security card have been used for nonwork-related purposes. For example, federal, state, and local governments require individuals to have a Social Security number to receive certain benefits or services, such as Supplemental Security Income, Temporary Assistance for Needy Families, and food stamps. Recent legislation provides strong incentives for states to include Social Security numbers on death certificates and drivers’ licenses, and private industry uses them for credit applications and insurance purposes, among other uses. In addition, the card is used to establish an individual’s eligibility to work in the United States. This range of uses has increased the potential for the number to be misused and the card to be counterfeited, causing concern in the Congress, which has, on several occasions, considered directing SSA to issue a more tamper-proof and less easily counterfeited card. Originally, SSA assigned a Social Security number to anyone based solely on the applicant’s unverified statements regarding age, identity, and place of birth, and issued everyone a card that contained the person’s name and Social Security number. Over time, SSA strengthened its requirements for assigning numbers and varied the information shown on the cards it issued. Since 1978, SSA has required applicants for original Social Security numbers to provide proof of age, identity, and citizenship or alien status. SSA later began printing legends, noting work restrictions on cards issued to noncitizens. Since 1982, SSA has provided Social Security numbers only to U.S. citizens, noncitizens authorized to work in the United States, and noncitizens with an approved nonwork reason for needing a number. Beginning in 1982, SSA printed “Not Valid for Employment” on cards issued to noncitizens who lacked work authorization but needed cards for nonwork purposes; and since 1992, it printed “Valid for Work Only With INS Authorization” on cards issued to noncitizens with temporary work authorization. Some Members of Congress have also been concerned about the public’s confidence in the Social Security system in general, and the message it sends to the public when the card is easily counterfeited and illegal uses of an individual’s Social Security number are easily made. In 1983, the Congress sought to combat illegal use of the number by passing legislation requiring SSA to develop its first counterfeit-resistant Social Security card. In response, SSA introduced counterfeit-resistant and tamper proof cards with security features including a blue tint random marbleized pattern, planchettes, and intaglio printing. Members of Congress subsequently expressed disappointment with the new card SSA developed, alleging that its security features did not make it significantly more difficult to counterfeit and that employers could not easily determine its authenticity for work authorization purposes. By law, illegal aliens—as well as legally admitted noncitizens, such as students and tourists—without valid INS work authorization are not entitled to work in the United States. To obtain a Social Security number and card, applicants fill out an application and submit evidence of their age, identity, and citizenship status or lawful alien status. Noncitizens must provide INS documentation authorizing them to work in the United States or a valid nonwork reason for needing a Social Security number, such as receipt of federal benefits. Applicants 18 or over are required to have an in-person interview and explain why they never obtained a Social Security number before. The Enumeration at Birth program allows parents to obtain a Social Security number for newborn babies through the hospital during the birth registration process. Applicant information is transmitted through the state to SSA, and a Social Security number and card are issued. When an individual’s card is lost or mutilated or the individual reports changes to information contained in SSA’s records (such as a legal name change after marriage), SSA issues a replacement card. However, unlike the process for issuing original cards, SSA does not verify the citizenship of individuals who indicate to SSA that they were born in the United States, as long as the information they previously provided to SSA supports their assertion. As a result, the process for issuing replacement cards does not provide for the cards to be reliable proof of the number holder’s entitlement to work in the United States. To receive a replacement card, an individual completes an application for a Social Security number and provides proof of identity, such as a drivers’ license, government or state identification, or school records. If, however, an individual is foreign-born and has not become a naturalized U.S. citizen, additional documents must be shown. These applicants must provide evidence of current lawful alien status and either INS work authorization or a valid nonwork reason for needing a number. SSA has issued new versions of Social Security cards while allowing existing cards to remain valid. As a result, current number holders may conceivably have one of 47 valid versions of the card that SSA has issued since the inception of the program. For example, cards issued before 1982 to noncitizens without work authorization do not contain legends indicating their lack of work authorization. The 40 versions of cards issued before 1983 lack counterfeit-resistant and tamper-proof security features. Likewise, cards issued before 1992 to noncitizens authorized to work for a limited time do not bear legends indicating their temporary work authorization. The Social Security trust funds have historically borne the costs of issuing original and replacement cards. SSA currently issues cards free-of-charge and does not limit the frequency or number of replacement cards. SSA has 1,300 field offices nationwide, which handle most applications for original Social Security numbers and replacement cards. While not labor intensive, handling Social Security number applications constitutes the largest volume of transactions for field offices. In fiscal year 1996, it cost SSA about $200 million to issue about 6 million original and 10 million replacement cards. However, under section 274A of the Immigration and Nationality Act (8 U.S.C. 1324a), payment for major changes, such as implementation of an enhanced counterfeit-resistant Social Security card, cannot be paid for by the trust funds or general appropriations. The Congress would need to specifically provide funding for such changes. Under the Immigration Reform and Control Act of 1986, employers are required to review documents that establish prospective employee’s identity and eligibility to work in the United States before hiring them.The law further requires employers to sign statements certifying that the documents they review appear genuine and refer to the prospective employee. The documents are provided by the prospective employees, and the law allows them discretion as to which of numerous approved documents they provide to employers. However, the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 required a reduction in the types of documents individuals can use to prove their identity and eligibility to work and gave the Department of Justice (DOJ) the authority to set conditions for implementing the reduction. To date, DOJ has eliminated some documents that previously could be used to establish eligibility to work, but implementation of this provision has not been completed. (See app. III.) Presently, the Social Security card, U.S. birth certificate, and U.S. passport remain the primary documents used by citizens to prove their eligibility to work. Noncitizens are currently limited to using either the Social Security card, if they possess one, or one of eight documents they may receive from INS that authorizes their employment. However, DOJ proposes to eliminate birth certificates from among the list of approved work eligibility documents. With these recent and proposed reductions in the types of work authorization documents allowed, reliance on the Social Security card as reliable proof of the prospective employee’s entitlement to work could increase the card’s vulnerability to forgery and misuse. On several occasions, the Congress has asked CBO and SSA to estimate the cost of issuing an enhanced card. CBO’s and SSA’s estimates have been widely divergent due to the assumptions each used regarding the number of people who would receive an enhanced card and the recognition of various costs in the issuance process. In 1994, SSA estimated that it would cost about $2.8 billion to $5.3 billion to issue enhanced cards to all 270 million number holders. This included $2.8 billion for processing the card and an additional $2.5 billion to include pictures or capture fingerprints on the cards. However, SSA’s estimates were much higher than some in the Congress anticipated they would be; so in 1996, a Member of Congress asked CBO for an independent estimate to coincide with proposed legislation making the Social Security card the primary work authorization document. In its 1996 informal staff-level estimate, CBO said it would cost SSA about $512 million to issue an enhanced card. These CBO and SSA estimates were so different that the Congress mandated SSA to develop a new estimate as part of the 1996 Illegal Immigration Reform and Immigrant Responsibility Act. The Congress also required GAO to develop its own estimate to compare with SSA’s. Our analysis of the CBO and SSA estimates shows that they are the result of very different assumptions, including the size of the population to whom the proposed card would be issued and consideration of ongoing card-processing costs. These differences make it difficult to compare the estimates. CBO’s estimate, for example, was for a single card option with security features similar to a drivers’ license, while SSA’s most recent and most comprehensive estimate considered seven different card options in response to the 1996 congressional mandate. In addition, CBO’s and SSA’s estimates were based on significantly different numbers of enhanced cards to be issued. CBO estimated the cost of issuing an enhanced card to 172 million number holders. These number holders consisted of 136 million people who CBO estimated would normally request original and replacement cards over an 8-year period, plus an additional 36 million people who it estimated would request the enhanced card.