All of the agency’s processing and taxpayer assistance centers have been shuttered to shield its workforce from exposure to the virus. With the normal tax filing deadline delayed until July 15, the IRS has turned most of its attention to implementing a key part of the federal government’s most recent economic rescue plan — sending out stimulus payments of up to $1,200 for individuals and $2,400 for couples, plus $500 for children under 17.

As a result, millions of individual taxpayers and businesses could face lengthy delays before they receive refunds they desperately need as the coronavirus halts their incomes. Taxpayers disputing how much they owe or waiting to see if they qualify for tax credits also could have to wait indefinitely.

“Clearly, most day-to-day operations at the IRS have stood down, that’s the blunt reality,” said a former commissioner, Mark Everson, who ran the agency from 2003 until 2007.