The federal Treasury continues to model a number of tax options, although its head is vague about whether that still includes changes to the GST.
Given government indications a hike in the GST was no longer on tax reform table, John Fraser was asked during a Senate committee hearing whether modelling was continuing.
"We have been asked to model a number or permutations and combinations ... it's not just about GST," he told an estimates hearing in Canberra on Wednesday.
Consultants KPMG and Independent Economics continue to assist Treasury in the modelling process.
Mr Fraser said he was waiting for direction from the government on how it intends to proceed with the tax reform process.
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"We were working on the basis there may be an option for a green paper and a white paper during the course of 2016," he said.
Finance Minister Mathias Cormann said the treasurer would announce the next steps "when he is in a position to do so".
Asked whether the budget would form the tax white paper, he said: "That is certainly a possibility."
