IACT says the process of routing tax dollars to the state and back again through payroll withholding may create other mistakes.
Of the dozen or so attendees at the public hearing Tuesday, almost all worked for the Department of Revenue. Only one person got up to speak.
The forum will be held in downtown Indianapolis in the state government center.
After two separate mistakes caused more than 500 million tax dollars to be misplaced, an independent audit of the state Department of Revenue will take place.
The deadline to file federal and state taxes is April 17.
Americans get three extra days to do their taxes this year.