A security camera hangs near a corner of the U.S. Internal Revenue Service building in Washington in May 2015. (Jonathan Ernst/Reuters)

At least 14,000 unpaid workers in the Internal Revenue Service division that includes tax processing and call centers did not show up for work this week despite orders to do so, according to two House aides, posing a challenge to the Trump administration’s ability to minimize the damage from the government shutdown.

The Trump administration ordered more than 30,000 employees back to work unpaid to prepare for tax filing season, which is set to begin next week. But of the 26,000 workers called back to the IRS division that includes the tax processing centers and call centers, about 9,000 workers could not be reached and about 5,000 more claimed a hardship exemption, IRS officials have told members of Congress, according to aides, who spoke on the condition of anonymity because they were not authorized to speak publicly about the numbers.

These numbers are as of Tuesday, according to the House aides, and the rate of employees returning to work may have changed since then. The IRS announced on Jan. 15 it would begin calling back workers as fears mounted about the IRS’s ability to process tax returns.

The shutdown appears to be affecting the IRS. In the call centers, which answer taxpayer questions over the phone, about 35 percent of calls are being answered, IRS officials told congressional staff, according to one of the aides. The initial plan for filing season was for 80 percent of calls to be answered. The average call time, of 7 to 10 minutes last filing season, has jumped to 25 to 40 minutes.

The IRS is also losing 25 IT staffers every week since the shutdown began, with many finding other jobs, one House aide said, citing the IRS officials' briefing.

An IRS spokesman declined to comment. News of the number of workers not showing up was first reported by Politico. The House Ways and Means Committee was briefed early Friday morning by IRS officials, who have also briefed the House Appropriations Committee.

IRS employees have said they cannot afford to get to work or pay for child care as they struggle to go more than 30 days without pay.

Absences among employees tasked with helping taxpayers understand the refund process are staggering.

Of the 1,700 accounts management workers who were called back to work in Kansas City and St. Louis, fewer than 600 have clocked in, said Shannon Ellis, president of the NTEU’s Chapter 66 in Kansas City.

The workers are missing shifts because they cannot afford the commute or child care, she said — and empty desks almost certainly mean delayed refunds.

“People are panicking,” she said. “It’s scary. It’s getting worse every day.”

Rosemary Bruscato, 50, who has worked at the IRS in Kansas City for 10 years, said “the majority” of her office is now out on hardship leave. She asked her boss for the exemption last week, citing the cost of gasoline.

She pays about $20 weekly to fill up her Ford Focus.

“That conversation was less than two minutes long,” she said. “There were no questions. Nothing that would make you feel uncomfortable. They just said, ‘Okay, you don’t have to report to work.’ ”