President Obama's plan to give work permits to young, illegal immigrants could cost nearly $585 million, according to internal Homeland Security Department documents obtained by the Associated Press.
It would also require the government to hire hundreds of employees to process the more than 1 million anticipated requests.
The president's plan is for immigrants who arrived in the United States before their 16th birthday.
They must have lived in the country at least five years, cannot be older than 30, and have no criminal record.
They must also be in school, graduated from high school, or served in the military.
Although the plans indicated there would be no waivers, Homeland Security Secretary Janet Napolitano told lawmakers waivers would be granted "in very deserving cases."
Critics note that such waivers could cost the government between $19 million and $121 million.
"By lowering the fee or waiving it altogether for illegal immigrants, those who play by the rules will face delays and large backlogs as attention is diverted to illegal immigrants," House Judiciary Committee Chairman Lamar Smith, R-Texas, said.
"American taxpayers should not be forced to bail out illegal immigrants and President Obama's fiscally irresponsible policies," he added.