The watchdog group told House staffers that the recovery would take between 12 and 18 months, one House aide said. These numbers assume the government does not shut down again in three weeks.
The IRS did not respond to a request for comment.
The Trump administration ordered more than 30,000 employees back to work without pay to prepare for tax filing season, which is set to begin next week. But about 8,000 workers have claimed a hardship exemption to not return to work, while an additional 5,700 workers could not be reached, the House aide said.
President Trump announced a deal on Friday to fund the government for three weeks, a deal that includes no additional funding for a wall along the U.S.-Mexico border. That plan cleared the Senate on Friday afternoon and was signed by Trump later that night.
But challenges to the IRS, as well as other agencies, are expected to persist after the longest shutdown in government history.
For instance, the IRS has a backlog of 5 million unanswered pieces of mail from taxpayers, up from 2.5 million on Jan. 16, IRS officials have told House aides. With in-person taxpayer assistance centers closed during the shutdown, the IRS was receiving more than 700,000 pieces of mail every day, up from 200,000 pieces of mail daily as of Jan. 16.
The government shutdown also delayed training for IRS employees, who must be taught how to implement changes to the tax code passed by Republicans in 2017. About 2,000 recently hired IRS employees also need to be trained before they can start answering taxpayer questions over the phone.
Concerns are also mounting over the service’s information technology, as a hardware glitch on Tax Day last year crashed the IRS’s online filing systems. The IRS is also losing 25 IT staffers every week since the shutdown began, with many finding other jobs, one House aide said, citing a briefing by IRS officials earlier in the week.
New regulations clarifying the more complex parts of the law have also come out at a significantly slower pace during the shutdown, and tax attorneys and accountants say they struggled to get IRS officials on the phone for help.
But some IRS employees are glad to be going back to work. Jenny Brown, a union leader and IRS employee in Ogden, Utah, has been concerned about her mortgage and car loan payments. She and four other IRS workers at home texted each other during Trump’s Rose Garden speech, hoping the rumors were true. A fifth called to ask if she was watching.
“Everybody’s happy. It’s great news, though we’re all like, ‘Is it signed yet? Is it signed yet?’ We’re ready for this to be over,” Brown said. “We’re ready to get back to work, and we’re looking forward to some pay. I just hope it doesn’t start again in three weeks.”