The Tai Tokerau MP says proposed changes to electricity transmission prices will mean people in Moerewa pay more for power, while Southland's Tiwai aluminium smelter pays less.
Kelvin Davis says the Electricity Authority's recent working paper on line charges reads like a recipe for corporate welfare.
Mr Davis says under all three options, Rio Tinto's power bill for the smelter drops by up to $11 million, but in the north, household power bills would go up by hundreds of dollars.
The MP said people living in places like Mitimiti, Te Hapua and Kaikohe should not be expected to subsidise a multinational like Rio Tinto.
Mr Davis said many low-income people could not afford to run heaters now - and if their bills went up even further, their health problems would only worsen.