And he also wants an enquiry into how much tax the rich actually pay, saying it is not well understood.
Parker, speaking at Victoria University, said there would be a new law to set out the principles of the tax system.
It would be a kind of oversight bill establishing proper standards of tax, but would not contain actual new taxes. It would be called the Tax Principles Act.
Questioned by his audience, Parker continued to reject a capital gains tax. Pushed on this further, he said the Prime Minister had ruled out a capital gains tax on her watch, and that would not change, since he, Parker, was himself “on her watch.”
But the new law would set out the principles of the tax system.
It would establish what Parker called standards of fairness in the tax system, and this process would be accompanied by new research into how the tax system actually works.
“The aim would be so that people can properly understand whether some people are paying more tax than they should, relative to others, or that some people are paying less than they should relative to others,” Parker said.
“This is not a pitch for new taxes because we are not planning any, we have emphasised that again today.
“It is trying to provide information to the public as to who is and who isn't paying tax.”
Parker then went on to say lack of clarity about tax payments of the very rich was an international problem.
“The reason why countries around the world haven't gathered good data on this is that there are some pretty powerful interests who quite like these answers being obscured.”
Parker added there was a poor quality of public debate about whether the tax system really was progressive and fair. This problem was made worse because much discussion of the matter was hampered by distorted information.
In another part of his talk, Parker rules out so-called hypothecated, or dedicated, taxes. He said petrol duties were one such tax, but these were not part of the Government's thinking in principle.
He also defended corporate tax levels, saying they might be high by international standards, but this was offset by dividend imputations.
And he said he wants the results of his inquiry into tax to be done before the next election.