There's a call for an independent agency that would put politicians' election spending promises under the microscope.

The Institute of Economic Research says the agency would decide if any policies were vague or couldn't be costed.

Principal economist Peter Wilson said it would also give a professional judgement on what each policy would cost.

"Be very transparent about the assumptions, be very transparent about the period you're costing it. Because that helps voters and that just gives them better information."

Wilson says it wouldn't be perfect information, but would be a lot better than what we get now.

LISTEN ABOVE AS PETER WILSON SPOKE WITH THE MIKE HOSKING BREAKFAST