The INTO, the country's largest teacher trade union, has decided to recommend rejection of the proposed public sector pay agreement.
The decision was taken at a meeting of the union's executive today.
The Government and public service unions reached agreement on a draft pay agreement yesterday which will cost €880m over the next three years or €1.1bn over four years.
The cost in 2018 will be €180m.
By the end of the agreement, 90% of public servants - those earning below €70,000 - will be out of the financial emergency FEMPI legislation.
A ballot of members, all primary school teachers, will begin next week.
In a statement the INTO said the move was based on the failure of the proposed agreement to progress the issue of pay equality.
INTO General Secretary Sheila Nunan said the union had made every effort to resolve this longstanding grievance.
Ms Nunan said: "Notwithstanding progress to date on pay equality, the recent pay talks were an opportunity to draw a line under pay discrimination and right a wrong imposed on new entrants since 2011.
"The agreement has failed to signal an end to pay inequality imposed by Government on recent entrants."
The INTO also said primary school principals had been waiting more than ten years for the payment of an independently awarded pay uplift to help end some of the large pay disparity between primary and post primary principals.
Ms Nunan said the proposed agreement offered little prospect of delivery on this issue, saying: "In recent years, work has intensified.
"More and more responsibility has been heaped on primary principals," she said.
As a result, she said the INTO Executive would recommend that its 36,000 members reject the proposed agreement in the forthcoming ballot.
Yesterday, another teacher's union, the TUI, also opted to recommend rejection of the proposed deal to its members.
The TUI represents around 15,000 second and third level teachers and lecturers.
TUI President Joanne Irwin said "An unwinding of the unacceptable, unfair and inequitable two-tier pay system was the key priority for TUI on entering the recent negotiations.
"It remains completely unacceptable to us that two colleagues, recruited within days of one another, are paid significantly different rates for carrying out the same work."