MANITOWOC, Wis. (AP) _ Georgeann Knier's tax bill would take a sizable chunk out of the national debt if she paid it.

She and her husband, Phil, got a notice Monday from the IRS: It said they owed $68,037,294,206.32.

''We couldn't believe it,'' she said Tuesday. ''We laughed hysterically.''

They were among taxpayers in five states affected by an IRS computer foul- up.

Donna Maggazi, an IRS spokeswoman in Milwaukee, said the error developed when the agency's Kansas City computers were adjusted to remove names of flood victims from lists of people paying taxes on installments.

Mistakes were made on an unknown number of reminder notices sent to Wisconsin, Illinois, Missouri, Iowa and Minnesota taxpayers, Maggazi said.

Richard Ostrander, 30, of Iron Ridge, was surprised when his bill says he owed $36 billion, including penalties and interest.

''I thought they were trying to get the deficit down in a hurry,'' he said.

Ostrander reached an IRS representative at a toll-free number and told him of his plight.

''When I told him about the bill, he laughed and placed me on hold for 20 minutes,'' Ostrander said.