Average household gas bills in Northern Ireland will increase by £11 a year following a decision by the Competition Commission.
The judgment resolves a dispute over future pricing between Phoenix Gas and Northern Ireland's Utility Regulator.
Phoenix wanted to raise customers' bills for 2012-2013 by £24 a year. The regulator intended to reduce domestic bills by around £1 a year.
Phoenix, which operates and maintains the gas network, said that would not allow them to make enough money to attract future investment into the firm.
The matter was referred to the Competition Commission and it has made its final judgment. For large businesses, this will add tens of thousands of pounds to their annual gas bill, the regulator said.
Regulator chief executive Shane Lynch said: "We will now carefully consider the detail of the Competition Commission's final determination and any implications for the next Phoenix price control, which will be implemented from 2014.
"More generally, and consistent with our principal statutory objective and the principles of good regulation, we will continue to work with DETI and other stakeholders to promote the economic development of the gas industry in Northern Ireland.
"In doing this, we will both protect consumers and ensure that efficient investment is adequately rewarded."