FIRMUS Energy has become the latest company to take complaints about the Utility Regulator to the competitions authority.
It comes after the energy watchdog put a curb on its spending plans over the next fives years.
The gas firm said it hoped the Competition and Markets Authority (CMA) review would be complete by the summer.
However, previous spats between the regulator and other energy companies such as Phoenix Gas and NIE dragged on significantly longer.
Firmus Energy did not specify exactly what aspects of the regulator's latest determination it had taken issue with.
It follows Firmus Energy's business plan for the five years to 2022.
It, along with Phoenix Natural Gas and SGN Natural Gas must have spending plans for the period - known as GD17 - passed by the watchdog.
It is understood both Phoenix and SGN have accepted the regulator's determination.
Firmus appeared to have been the biggest winners after months of negotiation following the Utility Regulator's draft determination.
The regulator agreed to £131.1 million in expenditure, against Firmus' initial £137m submission and significantly higher than the watchdog's £114m draft determination.
Firmus Energy managing director Michael Scott said: "Following the publication of the Utility Regulator’s final determination on Firmus Energy’s gas distribution business plan for 2017–2022 (GD17), and its decision to modify firmus energy’s gas conveyance licence to give effect to the final determination, we have requested that the Competition & Markets Authority (CMA) review certain aspects of the decision.
“It is expected that the outcome of this review will be concluded by the summer of 2017.”
