Summary: In recent years, growing public concern about illegal aliens in the United States has focused on their use of public benefits and their overall cost to society. The three national studies that GAO reviewed represent the initial efforts of researchers to estimate the total public fiscal impact of illegal aliens. The limited data available make it hard to develop reasonable estimates on such a broad subject. Moreover, the national studies varied considerably in the range of items they included and their treatment of some items, making their estimates difficult to compare. As a result, a great deal of uncertainty remains about the national fiscal impact of illegal aliens. Obtaining better data on the illegal alien population would help improve the national net cost estimates. Such data should focus on characteristics of illegal aliens, such as geographic distribution, age distribution, income distribution, labor force participation rate, tax compliance rate, and school participation, that are helpful in estimating the largest net cost items. Clearer explanation of which costs and revenues are appropriate to include would also help improve the usefulness of the estimates. The expert panel convened by the U.S. Commission on Immigration Reform could serve as a forum for discussing some of these data and conceptual issues.
