The Treasury Department this week released a new contingency plan to deal with the ongoing partial government shutdown, but Democratic lawmakers have doubts about the agency’s ability to handle the upcoming tax-filing season.

Treasury’s shutdown plan provides for 46,000 employees, about 57 percent of the agency’s workforce, to be working during tax-filing season, which begins Jan. 28. In addition to the challenge of IRS employees working without pay during the shutdown, this will be the first year that taxpayers will file returns that take into account major tax changes enacted at the end of 2017.

“I have concern about the IRS carrying out its mission,” said Sen. Ben Cardin (D-MD), a member of the Senate Finance Committee. “I want them to do that, and they can’t do it under a shutdown condition at the level it needs to be done.”

House Democrats said the IRS was scheduled to give Ways and Means Democrats a shutdown briefing on Jan. 16 but IRS Commissioner Charles Rettig canceled. The Treasury Department said they offered to have two deputy commissioners brief the committee but that offer was declined.