The tax working group's promise to stay away from inheritance is being labelled as a missed opportunity.

The terms of reference for the working group rule out income tax, GST, inheritance tax, tax on the family home, and international tax reform.

Inequality researcher Max Rashbrooke said while inheritance taxes are dwindling worldwide, they're an effective way to close the gaps.

"Mostly they don't affect the vast bulk of people, they just affect people who are going to inherit a really vast amount of money, and redistribute it to those who are a little less fortunate."

Max Rashbrooke said it'll be difficult for the working group to make fully-informed recommendations, when it has to ignore a number of politically sensitive topics.

"I think the working group can take some positive steps to address inequality, but it has been prevented from doing it's full job by the things that have been rolled out."

The Public Service Association also said the narrow scope of the government’s Tax Working Group is a disappointment.

However, property tax is in the sights of the Government's newly formed tax working group.

It also has climate change and environmental issues high on the agenda .

Partner at PricewaterhouseCoopers Geof Nightingale said it's likely more taxes are coming and the clear focus will be on how we tax property.