A bold move from the US government is being called a 'war on tax havens'.
Treasury Secretary Janet Yellen is calling for minimum global corporate tax of 21 percent across the OECD.
The change would provide big businesses with a single tax system, and major players like the world's richest man, Amazon's Jeff Bezos, is on board.
Business advocate Phil O'Reilly told Mike Hosking it would even the playing field for mega multinational businesses.
He says there's always been tax competition between economies, but it's seen some companies paying almost no tax in countries like New Zealand.
"There's always been tax competition between economies.What you have seen is these massive companies around the world paying basically no tax, and certainly very little tax in countries like New Zealand."
He says it's a question of getting everyone on board.
"A particular set of corporates, only the big guys - this would probably only apply to Fonterra. Then you've got to get everyone to agree. And then you've got to get those tax havens to agree."