Households nationwide are set to see an increase in electricity and gas bills as discount deals come to an end.
Around 130-thousand households could be affected when deals are withdrawn.
It could take between seven and eleven months for lower wholesale energy costs to wash through the system.
Paul Deane of University College Cork says there could be some costly increases on the cards:
"This could mean many of us will revert back to the premium tariffs which means we will see a significant increase in our electricity bills.
"Now what does this mean in terms of brass tax? It could be anything from a twenty percent increase or a thirty percent increase, converting that into euros it could be anything up to 500 euro across your bill if you don't keep an eye on it."