Those charged were: island owner Whakaari Management Limited and its directors Andrew, James and Peter Buttle, GNS Science, the National Emergency Management Agency, White Island Tours Limited, Volcanic Air Safaris Limited, Aerius Limited, Kahu NZ Limited, Inflite Charters Limited, I D Tours New Zealand Limited and Tauranga Tourism Services Limited.
The charges do not relate to events on the day of the eruption, or the rescue efforts.
At the last hearing in Whakatane District Court in June, only one of the defendants - the National Emergency Management Agency - was in a position to enter a plea.
Judge Evangelos Thomas directed the remaining defendants to file their pleas by Tuesday this week.
He confirmed today they all deny the charges they face.
The case is due back in court next month.
Judge Thomas has previously said a substantive trial is still some way off.