Restoring pay equality for teachers would cost almost €400m, the Department of Education and Skills has confirmed.
The contentious issue of the two tier pay system introduced for so-called new entrants almost a decade ago triggered Tuesday's strike by 19,000 teachers belonging to the Teachers Union of Ireland.
The Association of Secondary Teachers in Ireland, which took strike action on the issue in 2016, is also balloting to renew its mandate for industrial action.
Responding to a query from RTÉ News, a spokesperson for the Department said the cost of resolving the outstanding issues of concern for teachers over the next five years is estimated at approximately €398m.
He said this included both the cost of restoring the 'HDip allowance' and the cost of addressing outstanding pay scale issues.
Realigning the pay scales of pre- and post-2011 recruits would cost €328m, while reinstating the HDip Allowance would cost €14m a year or €70m over a five-year period.
The spokesperson noted that this estimate is based on current numbers employed, and would increase with the entry of any new teachers during this period.
It would also exclude the cost of eliminating two tier pay scales across the rest of the public service.
The spokesperson noted that the teacher unions have indicated that they have outstanding issues of concern following the September 2018 agreement which partially alleviated the gap between pre-and post 2011 recruits.
The spokesperson said the Government had given a commitment that these matters will be given full consideration, adding that that commitment remains.
He said the positions of each of the parties on these matters "must be given due regard in endeavouring to reach a mutually agreed resolution".
He added that the current series of restorative measures for new entrants has been achieved through continued engagement and collective bargaining between the Government and the public service unions, and showed the benefits that such engagement can bring.