The price of gas for Contact Energy customers is to rise by an average of between $11 and $49 a year from December.
Contact says the increase will begin from December and is due to changing distribution and transmission costs it says are out of its control.
Chief executive Dennis Barnes said like all gas retailers, Contact receives these charges from regulated gas distribution and transmission companies PowerCo, GasNet and Vector.
In December last year, Contact announced that it would not be increasing residential electricity or gas prices before a review in April 2015.
The network and transmission company changes relate to piped natural gas which in New Zealand is only available in the North Island.
