The tellers sitting behind the security glass at ACE Cash Express could be working in a bank, but the small linoleum-floored storefront has no deposit slips, financial advisers at desks, or even a carpet. Rather than getting a gift of $50, as I would if I were to open a checking account with direct deposit at Chase Bank before June 30, ACE would charge me between 2.5% and 10% to cash a check.

Customers at ACE are scared of getting the free account at Chase Bank. They don’t want the government to know that they even exist, much less that they receive regular paychecks. Many of them are undocumented immigrants, in America illegally, and they worry about being deported.

ACE and countless similar businesses throughout America are the big winners. The big losers are the American taxpayers.

Instead of regularly paying taxes to federal, state, and local governments, illegal immigrant workers — no one knows the exact number — are regularly paying fees to check cashing operations such as ACE.

American taxpayers also lose out to the “coyotes” who smuggle undocumented workers into our country from Mexico. If we were to set up a system of legal work visas, foreigners who want to work here could pay the government for these permits rather than pay coyotes for unsafe, illicit transportation. Funds from the permits could be used to buy health insurance, education, and biometric identification cards for legal workers.

These are just some of the costs that governments could recoup by legalizing undocumented workers. Rather than deporting immigrant workers in horrific scenes of parents being separated from children, as was the case in the raids on the Swift meatpacking plants in Colorado, Nebraska, Texas, Utah, Iowa, and Minnesota, we could have a rational immigration system of which all Americans could be proud.

To begin, the first requirement of a rational American immigration policy should be that benefits exceed costs. On exactly this point, two days ago the president’s Council of Economic Advisers released a study showing that the benefits of immigration more than outweigh the costs. According to CEA, Americans gain $37 billion per year — or more than $150 per person — from current immigration policies.

The CEA conclusions do not reflect just the careful analysis of the administration’s market-oriented economists.

The Congressional Budget Office, headed by Peter Orszag, an economist closely identified with the Democratic Party, also finds that the proposed comprehensive Senate immigration bill would benefit the federal budget. If Congress legalized immigration, then we taxpayers would come out ahead financially.

Indeed, the reasoned economic analyses by those of any political persuasion consistently find what economics students learn in the classroom — the unfettered movement of people and free trade under reasonable conditions enhances the welfare of practically everyone.

The second element of a rational immigration policy would have immigrants cover their own costs. Some of the greatest costs that illegal immigration imposes on society are health care costs.

If immigration were legal and better controlled by government, payments for health care through insurance could be collected more easily. Currently, the large health care and other costs of a relatively small number of immigrants are shifted to society rather than being paid by the individual immigrants who get health care services in hospital emergency rooms.

This is not just an immigrant problem — it also needs to be addressed for uninsured native-born Americans. President Bush has proposed decoupling health insurance from employment and providing everyone with a tax credit to purchase health insurance. He also wants to allow professional associations to sell health insurance policies across state lines.

The third element of a rational immigration policy would include clear incentives to being documented and paying taxes. Such incentives might include social services linked to some form of legal documentation, and fines or deportation for those caught without papers.

This sort of immigration policy would improve America’s security. Now, with an estimated level of 12 million undocumented immigrants, it’s practically impossible to identify the small minority who wish us harm from the majority who come to find work. Being able to work legally and get official identification — and bank accounts — would make it far easier to identify and track potential terrorists, dubious financial transactions, and those who simply overstay visas.

Practically everyone would win with this kind of policy except ACE Cash Express and similar businesses that exist merely because many prefer to be excluded from our financial system.

The immigration bill that the Senate will consider next week isn’t perfect. But if you believe that immigrants should pay the costs of their services, that people should deposit their pay checks in banks and pay income taxes, and that national security would benefit from greater transparency, then you should hope the Senate succeeds in its efforts to change the current law.

Ms. Furchtgott-Roth, former chief economist at the U.S. Department of Labor, is a senior fellow at the Hudson Institute.