Updated

The Obama administration's plan to let thousands of young illegal immigrants stay in the country and apply for work permits reportedly could cost more than $585 million to carry out.

According to internal documents obtained by The Associated Press, illegal immigrants will be able to request permission to stay in the country and apply for a work permit starting Aug. 15.

U.S. Citizenship and Immigration Services could receive more than a million applications in the first year alone, costing $467 million to $585 million to process.

Most of that is expected to be paid with fees from the applicants. The report estimates the fees will add up to $484 million -- though this still leaves a shortfall.

Waivers of the plan's $465 paperwork fee could dramatically affect the government's share of the cost. The plans said there would be no waivers, but Homeland Security Secretary Janet Napolitano told Congress last week that the government would grant waivers "in very deserving cases."

Republicans pounced on the possibility that taxpayers could foot at least part of the bill.

"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 said. "American taxpayers should not be forced to bail out illegal immigrants and President Obama's fiscally irresponsible policies."

The Department of Homeland Security, though, claimed the program has to be covered by applicant fees and "will not require any taxpayer dollars."

Spokesman Matthew Chandler also noted that the process is "not final."

"Preliminary documents should not be confused with final operational decisions, and any cost estimates do not reflect final decisions of the department or the actual volume of requests," he said. "As the administration has repeatedly made clear, USCIS is a fee-based agency and the adjudication of deferred action application requests will not use taxpayer dollars."

The government estimated that as many as 890,000 immigrants in the first year would be immediately eligible to avoid deportation.

Once immigrants submit their applications, it could take two to 10 days for the Homeland Security Department to scan and file them. It could take up to four weeks longer to make an appointment for immigrants to submit their fingerprints and take photographs. A subsequent background check could take six more weeks, then three more months for the government to make its final decision before a work permit would be issued.

Napolitano said new information about the program should be made available by Aug. 1. She has said immigrants would generally not be detained by immigration authorities while their applications are pending.

The Associated Press contributed to this report.