Westpac bank economist Michael Gordon says the Reserve Bank should be intervening more in the currency markets.
Mr Gordon says the Reserve Bank should not necessarily be to try and change the trajectory of the dollar, but to make money for the taxpayer.
Since being given extra powers in 2004 to intervene directly in the currency markets, to prevent excessive volatility in the dollar, the Reserve Bank has exercised them only twice, in 2007, and in 2008.
Other, smaller interventions, to manage its foreign exchange reserves, have been only slightly more frequent.
Mr Gordon believes it should be doing more. He says there is a case for intervening in the currency, and that case is 'to make a buck for the taxpayer'.
"That's a matter of is the Reserve Bank sufficiently well informed to be able to identify when to buy and when to sell and I think they actually are".
He says the Reserve Bank's policy has been to sell near the top and buy near the bottom and make a return over the longer term.
Mr Gordon says he's surprised the Reserve Bank hasn't taken the opportunities that have arisen over the last couple of years.
He says that reluctance shows the bank's increasing wariness of intervention as a policy.
Just last month the Reserve Bank said interventions by the Swiss and Japanese since 2009, were tried under very different economic conditions than in New Zealand, and to do the same here would have been counterproductive.
It also pointed to large unrealised losses by those countries' central banks.
The Reserve Bank says it has accumulated in the past two years unrealised losses totalling $400 million on foreign reserves built during its own interventions.
Although it more than covered those losses from profits in the preceding two years.
It has since reduced its unhedged foreign exchange reserves, lessening its exposure to fluctuations in the currency.