In articles in The Tax Lawyer, a publication of the American Bar Association, and in the upcoming issue of the Harvard Latino Law Review, Francine Lipman, a professor at Chapman University's law school in Orange, Calif., writes that the widespread belief that undocumented immigrants cost us more than they give us is "demonstrably false."

In her review article, Lipman wrote that there are 7 million undocumented workers, which is 1 out of every 20 in the United States. Such undocumented workers live in households in which the average annual income is $27,400, compared with nearly $48,000 for legal immigrant families.

They cannot access or easily access many public services, yet in 2003 alone the labor of undocumented workers poured $7 billion in taxes into Social Security, even though they cannot legally claim those benefits. Lipman calls this "an abyss in federal relief for hard-working, poor families. Undocumented working-poor families have higher effective income tax rates than their neighbors who enjoy higher income levels."

They perform jobs that are inseparable from our standard of living. Undocumented workers are about 5 percent of our overall labor force, but according to the Pew Hispanic Center's analysis of Census data, they are between 22 percent and 36 percent of America's insulation workers, miscellaneous agricultural workers, meat-processing workers, construction workers, dishwashers and maids. The American Farm Bureau, the lobbying group for agricultural interests, says that without guest workers, the United States would lose $5 billion to $9 billion per year in fruit, vegetable and flower production and as much as 20 percent of production would go overseas.

Often ignored by anti-immigration forces is the fact that undocumented workers pay sales taxes and real estate taxes--directly if they are homeowners, indirectly if they are renters. Analysts at Standard & Poor's wrote recently that there is no clear correlation between undocumented families and local costs, as the states with the highest numbers of such families also have relatively low unemployment rates, high property values and strong income growth, "all of which contribute to stable financial performance."