The Greens say they've 'had words' with one of the country's most well-known economists over a maths mistake in its tax policy.

It's issued a correction, saying the policy released yesterday will increase net revenue $5.15 billion dollars in the 2027/28 financial year - not $5.35 billion. 

Co-leader Chlöe Swarbrick says consultancy Infometrics - headed by Brad Olsen - had the job of analysing the policy figures. 

"It was supposed to be our insurance. This is, I think, just human error - and I know that Brad is also more than willing to front up for this."

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