The Electricity Authority has new figures that show North Islanders paying more than their southern counterparts for power will add about $40 million more to the country's coffers than previously thought.
The authority wants to change the way people pay for New Zealand's transmission system.
The 12,000km network of high voltage wires, which carry power around the country, costs $918 million a year.
That money is paid as a percentage of everyone's power bill.
The authority's proposal meant people who benefited from expensive grid improvements - such as Aucklanders - would pay more.
Those who did not have expensive upgrades to their system - such as people in the lower South Island - would pay less.
In its calculations, the authority said the geographical divide would benefit New Zealand as a whole.
Australian consultants assessed the benefit at $203.3m, but new figures from the consultants put it at $241.9m.
That was about $40 million more.
It was a long-term figure, based on present day values and the proposed pricing system's ability to deter inefficient investment.
Debate over a new transmission pricing system has gone on for years.
It is nearing its conclusion, but another round of counter submissions by companies and others affected by the changes must still be considered.