The Internal Revenue Service’s electronic system that allows Americans to submit their tax returns online has partly failed Tuesday, complicating filing for the millions of Americans attempting to meet the midnight deadline.

“On my way over here this morning, I was told a number of systems are down at the moment,” IRS Acting Commissioner David J. Kautter told lawmakers at an IRS oversight hearing Tuesday. “We are working to resolve the issue and taxpayers should continue to file as they normally would.”

The IRS plans to attempt a “hard reboot” of its system in the hope of solving the problem, according to a congressional official who spoke on the condition of anonymity to describe private conversations.

“If we can’t solve it today we’ll figure out a solution,” Kautter said. “Taxpayers would not be penalized because of a technical problem the IRS is having.”