The U.S. Internal Revenue Service said on Thursday it had resumed processing individual and business tax returns at about 5 p.m. EST on Thursday after a system outage.
The IRS said on Wednesday it was experiencing computer failure across several systems and temporarily could not accept many taxpayer returns.
"IRS teams worked throughout the night and around the clock on this system outage," IRS Commissioner John Koskinen said. "Our processing systems are back in business. Taxpayers should see little, if any, impact on their tax returns or refunds," he added in a statement.
The U.S. federal tax collection agency said it was continuing to examine the cause of the outage, but that it appeared to have been a hardware failure.