The Internal Revenue Service said it would give U.S. taxpayers an extra day to file their returns electronically after a computer malfunction disrupted the agency’s website.

The IRS said in a statement on Tuesday evening that its processing systems were back online, and that the new deadline was Wednesday.

Every year the IRS processes more than 120 million tax returns that arrive by mid-April and spits back some $300 billion in refunds. Last year, about 90 percent of returns submitted by April 21 were e-filed, according to IRS data. Tax Day was on April 17 this year, since April 15 was a Sunday and April 16 was a holiday in Washington.

Bruce Friedland, a spokesman for the IRS said in a statement on Tuesday afternoon that “all indications point to this being a hardware-related issue, not other factors.”

The IRS is unable to accept information transmitted from software providers, David Kautter, acting commissioner of the IRS, said after testifying at a congressional hearing on Tuesday.

“On my way over here this morning, I was told a number of systems are down at the moment,” Kautter said during the hearing. The problem was discovered between 1 a.m. and 3 a.m., according to Kautter.

The systems that malfunctioned included e-file and direct pay, which allows taxpayers to pay what they owe through their bank accounts, Friedland said.