While the justification for passing these anti-immigrant laws was to save taxpayer money, follow-up studies have shown little evidence of any savings -- hardly surprising since there was little evidence beforehand that undocumented immigrants were receiving so many benefits. ID requirements are usually so extreme that many legal citizens are turned away. For example, Colorado passed a law that prevented state agencies from even accepting a U.S. passport as documentation to obtain a driver's license, leading to the irony that one of the state's main proponents of the bill saw his daughter rejected  for a license. The sad result, as the National Immigration Law Center notes , is that "U.S. citizens are less likely than noncitizens to have the documents required by the new verification laws." (p.7) While the law was amended to allow passports and a few other documents, the law has still inflicted burdens, both financial and personal on citizens of the state.
In fact, one study in Colorado found that the law there was costing the state an additional $2 million in increased administrative costs without any identifiable savings . In Kansas, the Wichita Eagle  highlighted that Kansas spent $1 million last year to comply with federal proof-of-citizenship requirements for the state SCHIP program and found only one undocumented immigrant using the program. And as an article  in USA Today emphasized, the reality is that anti-immigrant proposals may be discouraging families from getting early treatment for sickness or injuries, just increasing the cost when they show up at the hospital in an emergency.
But, if such ID rules save the taxpayers little money, the impact on legal residents and citizens can be severe. This was highlighted when the federal government imposed new identification requirements for new applicants for Medicaid. The result? Initial estimates  were that 1.2 to 2.3 million citizens lacked the documents required by the new rules and were in danger of losing coverage. Follow-up studies by both the Center for Budget and Policy Priorities  and the Government Accountability Office (GAO)  found that Medicaid rolls declined in 44 states after Congress imposed the new requirements -- and most of those losing coverage were legal residents eligible for coverage but unable to produce the necessary documents. For other social programs covered by the states with the new anti-immigrant laws, confusion and fear led people to lose other benefits. States should commission their own studies to show the impact of benefit ID laws in hurting legal residents of their states.
- Progressive States, Kids are collateral damage in immigration witch hunt 
- Center on Budget and Policy Priorities, New Medicaid Citizenship Documentation Requirement is Taking a Toll: States Report Enrollment is Down and Administrative Costs Are Up 
- Government Accountability Office (GAO), Medicaid: States Reported that Citizenship Documentation Requirement Resulted in Enrollment Declines for Eligible Citizens and Posed Administrative Burdens  (June 2007)