So how do they do it? Oxfam's investigation says by profit shifting. That's when firms make profits in one country and shift them across borders by exploiting gaps and mismatches in tax rules.
"This is not tax evasion, it's tax avoidance and it's legal within our current rules in New Zealand this is something multinationals are able to do all round the world," Ms Le Mesurier said.
The Oxfam investigation shows RB restructured its business to create regional hubs in the Netherlands, Singapore and Dubai.
"Before they restructured they were clearly making good profit ... they were doing very well in New Zealand ...in the last three years what it looks like is their profits have dropped off a cliff," Ms Le Mesurier said.
None of this is illegal, of course - as with MP's rorting their travel and entitlements, it's all within the rules. But it is immoral, a betrayal of the social contract. And we should respond by taking our money elsewhere until RB pays its fair share.