The plastic bag levy is set to be doubled to 44 cent.
The Department of Environment has indicated that a Bill to give force to the new levy will be published next month.
A spokesman for the department said it was expected that legislation paving the way for the increase would then be in place by the end of this year.
The levy was first introduced in March 2002 at a rate of 15 cent per bag.
In 2007, the levy was increased to 22 cent.