The rule change—long in the works, and long opposed by anti-poverty nonprofits, legal-aid groups, immigration advocates, social-justice organizations, and many others—is a technical one. The 447-page proposal would make caseworkers consider the legal use of public benefits as a “heavily weighed negative factor” in considering whether to grant an immigrant entry to, or the right to remain in, the country. It would affect 400,000 people a year, the administration estimates, among them prospective and current legal immigrants.

Immigration experts anticipate that the maneuver would make it harder for low-income families to come to the United States and would scare immigrants away from the safety net—with profound repercussions for their health and well-being, and a profoundly disparate impact on communities of color. Among those who would likely avoid seeking government aid, they said, would be the millions of mixed-status families, with both citizen and non-citizen members, already here.

The proposal’s mathematics are brutal and zero-sum, implying that a dollar spent helping an immigrant is a dollar not spent helping a native-born American and that immigrants are a drain on public resources. This is not at all the way that the numbers add up. For one, because the government runs deficits nearly every year, your average American is a drain on Uncle Sam, not just your average immigrant. The American people do not provide a net fiscal benefit to the government, regardless of their citizenship or legal status.

Further, the government’s resources are not “finite.” Immigrants do not come and steal things away from native-born Americans. Immigrant families pay taxes. They work. They start businesses. They spend money in their communities. They join native-born families in being economically productive, both paying money to the government and receiving benefits from the government.

Do they receive more than they take—that is, are they a net drain? Again, the answer is no. Lower-income immigrant families might receive more in benefits than they pay in taxes. But that mathematical equilibrium is temporary, and an artifact of the way the tax-and-transfer system is structured to help lower-income families and to support families with kids. As one Federal Reserve summary of the research puts it: “If immigrants are assigned the marginal cost of public goods, then the long-run fiscal impact is positive and the short-run effect is negative but very small (less negative than that of natives).” Given some time in the country, these families pay in, in other words. One estimate puts the net present value of each immigrant to the government at $259,000. The Trump administration would prefer a smaller country, a smaller economy, and a more perilous long-term fiscal picture, evidently.