The tax collector has so far denied the request because of concerns it violates taxpayer privacy laws.
The Department of Homeland Security has pushed the Internal Revenue Service to turn over the addresses of roughly 700,000 undocumented immigrants it is seeking to deport, according to three people familiar with the matter, in a request that could violate taxpayer privacy laws.
I.R.S. officials have so far denied the department’s attempts to verify the addresses, the people said, because of the legal concerns. But the request is part of a broader effort by the Trump administration to enlist the tax collector in its plans for mass deportations.
Many undocumented immigrants file tax returns with the I.R.S., giving the agency information about where they live, their families, their employers and their earnings. The I.R.S. gives immigrants without Social Security numbers a separate nine-digit code called an individual tax payer identification number to file their returns.
Taxpayer information is typically kept closely held at the I.R.S., with improper disclosure barred under federal law. I.R.S. officials have told their Department of Homeland Security counterparts that they need to follow rules governing taxpayer privacy, the people familiar with the matter said.
Representatives for the I.R.S. and the Department of Homeland Security did not immediately respond to a request for comment. The Washington Post reported earlier on the request.
The request is a sign of the lengths Trump administration officials are trying to go to deport millions of immigrants in the United States illegally. Administration officials are preparing to create a registry listing migrants and are using military sites to help deport them.
The Trump administration has repeatedly sought access to taxpayer information at the I.R.S. in ways that officials at the tax agency have worried could violate federal law. The agency recently signed an agreement allowing a member of Elon Musk’s Department of Government Efficiency to view anonymized taxpayer data as part of a push to modernize the agency’s software. The Musk team is leading an effort to shrink federal programs and the government’s work force.
The Department of Homeland Security had previously tried to enlist I.R.S. agents in its broad immigration crackdown, asking for agents to audit companies that might be hiring unauthorized immigrants, according to a copy of a memo viewed by The New York Times. President Trump has also suggested that I.R.S. agents could be sent to the border with Mexico.
The requests have added to the tumult at an agency that is already reeling. The I.R.S. has been hit with more than 7,000 layoffs under the Trump administration so far, and its acting commissioner, Doug O’Donnell, stepped down on Friday, the second resignation at the top in little more than a month.
Mr. Trump and Mr. Musk have both suggested that the I.R.S. should be abolished.