As President Biden charts his coronavirus economic recovery agenda through the Internal Revenue Service, the nation’s tax collector will take on an expanded role as comptroller of the social safety net, delivering billions of dollars in stimulus payments to millions of American households.

Under the “American Rescue Plan,” the Biden administration plans to use the IRS to distribute a third round of economic impact payments to 84 percent of American households. The agency could also be tasked with executing a proposal to distribute $120 billion in child benefit payments every month.

But the mission threatens to stretch the agency between its primary role as the country’s chief revenue collector and its relatively new presence as the distributor of coronavirus relief.

The reliance on the IRS comes at a time when the agency is already underfunded and scrambling in pandemic working conditions.

It continues to grapple with a significant backlog from the 2019 tax-filing season, plus snags in earlier rounds of stimulus payments. Personnel shortages caused by the pandemic have also caused a major slowdown in agency operations, forcing officials to platoon staff at IRS campuses to open mail and process a backlog of paper returns…