Operating on the assumption that 20 percent of undocumented immigrants would leave voluntarily, the report said deporting the remaining 80 percent—8.96 million people—would cost between $103.9 billion and $303.7 billion.
That figure includes, over the next 20 years, $243.3 billion for apprehension, $35.7 billion for detention, $13.4 billion for processing and $11.3 billion for transportation home. On top of that amount, the government would have to spend $315.7 billion on keeping new immigrants from entering the U.S. without proper documentation.
Although more difficult to calculate, the report said mass deportation also would negatively impact the federal deficit. Undocumented immigrants, about half of whom are taxpayers, are contributors to social services but are low users of those services.