Former Treasury secretary Ken Henry has warned of a looming "crisis" in Australia's taxation system, and says there is an urgent need for changes.

Dr Henry authored a major review of the tax and payments system in 2010, which was commissioned by the former Labor government and became known as the Henry Review.

It recommended simplifying and abolishing taxes as well as streamlining welfare payments for an ageing population.

Speaking at a forum at the Australian National University on Tuesday, Dr Henry expressed frustration that so little progress had been made.

"The tax review that I was associated with - that I had the pleasure of leading - it identified a number of medium-term challenges confronting the Australian economy and it identified pathways for future tax reform," he said.

"And it said there was no urgent case for moving at that time.

"We're getting much closer to that point at which we should acknowledge that ... there is an imminent crisis ahead for the tax and transfer system and therefore there is a strong case for developing a comprehensive tax and transfer reform package."

Dr Henry suggested the Abbott Government take another look at his 2010 review, which he described as a "comprehensive" document.

"It covers all elements of the tax system, obviously not the GST, and it covers the entire transfer payments system as well, there's a lot in that document I think," he said.

The Prime Minister has promised another review of the tax system, which will include the Goods and Services Tax, although he has previously said there would be no changes in the Coalition's first term.

Dr Henry said at some point, the GST needed to be looked at, adding that he thought that was "inescapable".

But he acknowledged the Government needed to get the public onside before introducing major changes.

"I think it's very important that a government does have a mandate if it is going to effect large-scale reform," he said.

The Federal Government has repeatedly warned the budget situation is dire, and one area under review is the indexation rate of the Disability Support Pension, given that it increases more quickly than unemployment benefits.

Dr Henry said this was an issue identified in his 2010 review.

"That problem's been known for many, many years, and the problem is just getting bigger and bigger as each year goes by, so at some point it's going to have to be looked at," he said.

"Obviously the Government has to consider it. Whether it decides it's the appropriate thing to do is going to be as much a political consideration as anything else obviously."