Talk about bad timing. Technical difficulties have hit the Internal Revenue Service as people across the United States are trying to file their 2015 taxes.

The agency said Wednesday it experienced a hardware failure that brought down some of its tax processing systems, including the one that enables people to file their returns electronically.

The IRS said it was trying to fix the problems but warned some of the systems were likely to remain down until Thursday.

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The IRS isn't exactly at the cutting edge of tech. Thanks to persistent budget cuts, the agency's efforts to modernize its technologies have been held up, IRS Commissioner John Koskinen told a Senate panel in February 2015.

"We're running applications we were running when John F. Kennedy was president," Koskinen told lawmakers when asked why there had been a delay in sending out new tax identification numbers to victims of identity theft.

He also said some IRS systems still use the COBOL programming language, which Computer World once described as "a programming dinosaur that was last hot in the 1980s."

When one senator asked how the agency could still be using such old systems when it spends over $2 billion a year on information technology operations, Koskinen explained that the money has been going into upgrading its systems, which were customized for the IRS in the 1950s and 1960s.

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During Wednesday's technology headache, the agency's website was available, but it said some services -- such as "Where's My Refund" -- were not.

The IRS said it does not anticipate major tax refund disruption.

"We continue to expect that 9 out of 10 taxpayers will receive their refunds within 21 days," it said.

Taxes are due on April 18 this year.

- Jeanne Sahadi contributed to this report