Hundreds of Internal Revenue Service employees have received permission to skip work during the partial government shutdown due to financial hardship, and union leaders said Tuesday that they expected absences to surge as part of a coordinated protest that could hamper the government’s ability to process taxpayer refunds on time.

The Trump administration last week ordered at least 30,000 IRS workers back to their offices, where they have been working to process refunds without pay. It was one of the biggest steps the government has taken to mitigate the shutdown’s impact on Americans’ lives.

But IRS employees across the country — some in coordinated protest, others out of financial necessity — won’t be clocking in, according to Tony Reardon, president of the National Treasury Employees Union, and several local union officials. The work action is widespread and includes employees from a processing center in Ogden, Utah, to the Brookhaven campus on New York’s Long Island.