By ROBERT PEAR
 
ASHINGTON, Aug. 9 - The federal government is offering $1 billion to hospitals that provide emergency care to undocumented immigrants. But to get the money, hospitals would have to ask patients about their immigration status, a prospect that alarms hospitals and advocates for immigrants.

When Congress decided to provide the money last year, state officials and hospital executives saw it as a breakthrough. For years, they had argued that the federal government was responsible for immigration policy and should cover the costs of medical care for illegal immigrants because it had created the problem. These costs weigh heavily on border states like Texas, Arizona and California and on states like New York and Illinois, with large numbers of such immigrants.

The largest allocations are going to California, $72 million a year; Texas, $48 million; Arizona, $42 million; New York, $12 million; Illinois, $10 million; and Florida, $9 million.

But federal health officials, under guidelines developed in the last couple of weeks, said hospitals had to ask questions about immigration status to make sure the money would be used as Congress intended, for "emergency health services furnished to undocumented aliens."

Hospital executives and immigrant rights groups said the questioning would deter undocumented immigrants from seeking hospital care when they need it, and some hospitals said compliance might cost them more than they would receive in federal aid.

Marcela G. Urrutia, an analyst at the National Council of La Raza, a Hispanic civil rights group, said: "We are extremely concerned about this requirement. It will deter Latino communities from seeking emergency care. That could lead to serious public health problems, including the spread of communicable diseases.''

Janelle R. Howard, a spokeswoman for Carondelet Health Network, with hospitals in Tucson and Nogales, Ariz., said: "Our emergency rooms see a lot of undocumented immigrants, including some picked up in the desert. But as a Catholic institution, we have never asked about their immigration status. It's our mission and philosophy to treat all without distinction.''

Under a 1986 federal law, a hospital has to provide a medical examination and treatment to stabilize the condition of any patient who requests care in its emergency room, regardless of the person's ability to pay. Hospitals often absorb the costs when patients have no insurance or other source of payment.

The Department of Health and Human Services wants hospitals seeking reimbursement to ask patients these questions, among others:

¶"Are you a United States citizen?''

¶"Are you a lawful permanent resident, an alien with a valid current employment authorization card or other qualified alien?''

¶"Are you in the United States on a nonimmigrant visa'' of the type issued to students, tourists and business travelers?

¶"Are you a foreign citizen who has been admitted to the United States with a 72-hour border crossing card?''

Hospital employees would have to sign forms certifying that the immigration information for each patient was "true and complete'' to the best of their knowledge. Hospital administrators who knowingly submit false information to the government would be subject to civil and criminal penalties.

Under the new guidelines, photocopies of passports, visas, border crossing cards or other documents that establish the patient's status should, if available, be included in the patient's file.

Patricia J. Wang, senior vice president of the Greater New York Hospital Association, said: "I don't think any hospital will be able to get that type of information from immigrants. It's like ringing a bell in their face if you ask directly, 'Are you a U.S. citizen, are you a lawful permanent resident?' ''

Hospitals collect a variety of demographic and clinical information on patients, including details of any insurance they might have. But hospitals say they generally do not ask patients about their immigration status.

The new program, created under the 2003 Medicare law, presents a conundrum: To get federal money, hospitals will have to document the citizenship status of an undocumented population - an inherently difficult task.

Immigration experts said the questions could befuddle immigrants and some hospital employees. "Those are some pretty technical questions to ask an ailing, not highly educated person,'' said David A. Martin, former general counsel of the Immigration and Naturalization Service, who is a law professor at the University of Virginia.

Angela D. Hooton, a lawyer at the Mexican American Legal Defense and Educational Fund, said, "Undocumented immigrants fear that if they answer such questions, the information might be used against them in deportation proceedings.''

Federal officials emphasized that data on individual patients would not ordinarily have to be submitted to the government, but they also said that hospitals must keep it on file so federal auditors could check the information. The government said it had a legal obligation to prevent "inappropriate, excessive or fraudulent payments.''

Dr. Mark B. McClellan, administrator of the federal Centers for Medicare and Medicaid Services, said hospitals could ask the questions in "an unobtrusive way'' that would not discourage immigrants from seeking care.

But hospital executives said they would probably have to ask all uninsured emergency patients about their citizenship or immigration status. The government says hospitals must not single out people who "look or sound foreign.''

Lawyers say such disparate treatment could violate the Civil Rights Act of 1964, which prohibits discrimination on the basis of race, color or national origin in programs that receive federal aid.

Hispanics are less likely to have health insurance than other racial and ethnic groups. The Census Bureau says that 32 percent of Hispanics are uninsured, compared with 20 percent of blacks and 11 percent of non-Hispanic whites. Among Hispanic noncitizens, the proportion is even higher. About 55 percent are uninsured, the bureau says.

Immigrants can significantly affect public health. The foreign-born population accounts for a growing share of tuberculosis cases in the United States - 53 percent of the 14,871 cases reported last year, according to the federal Centers for Disease Control and Prevention.

In many immigrant households, at least one parent is undocumented, but the children, having been born in the United States, are citizens.

When such families hear about the questions asked by hospital employees, Ms. Urrutia said, "it's likely that the undocumented immigrant parents will be terrified to seek care for their children, let alone themselves.''

Similar fears swirl around the census every 10 years. Immigration officials sometimes cut back raids and other enforcement activities when census takers try to count the population in neighborhoods with large numbers of immigrants.

The health care money will be made available in four annual installments of $250 million, for services provided on or after Oct. 1.

Hospitals say it may cost them more to comply with the new regulatory requirements than they will receive in federal aid. "We might spend more money documenting the care we provide to immigrants than we get back to pay for it,'' said Jan Emerson, a spokeswoman for the California Healthcare Association, which represents 450 hospitals.

Some public hospitals say the federal money will cover only 10 percent to 15 percent of the costs they incur providing emergency care to undocumented immigrants.

Some hospital executives say that, instead of asking detailed questions, they should be allowed to make reasonable inferences. For example, they say, a hospital might conclude that a patient was an undocumented immigrant if the person was born in another country and had a foreign driver's license, a foreign address and an invalid Social Security number.

Other hospitals want to use a mathematical formula to estimate the costs that qualify for reimbursement, without having to collect the immigration information needed to submit a separate claim for each patient.