Treasury Department officials are considering rolling back a tax rule aimed at preventing American companies from moving money offshore to avoid U.S. taxes, according to several people familiar with discussions.

Major U.S. banks shaved about $21 billion from their tax bills last year -- almost double the IRS’s annual budget -- as the industry benefited more than many others from the Republican tax overhaul.By year-end, most of the nation’s largest lenders met or exceeded their initial predictions for tax savings.

The U.S. Treasury Department is set to maintain elevated sales of long-term debt to finance the government’s widening budget deficit, with new issuance projected to top $1 trillion for a second-straight year. A heightened supply of Treasury securities follows tax cuts and government spending increases implemented under the current administration. That’s darkening a fiscal outlook already made worrisome by rising entitlement-program expenses and higher costs to service America’s nearly $16 trillion in debt.