The Teachers' Union of Ireland says it will ballot members for an industrial action mandate as part of their efforts to secure pay equality for second-level teachers.
The TUI - which represents around 18,000 teachers - says next month's ballot will look to renew a mandate for action up to and including strikes.
Members previously voted for industrial action in September 2017, but the union's now seeking a 'refreshed' mandate.
While acknowledging progress has been made in addressing the pay gap, the union says new entrants employed from 2011 earn 10% less in their first 10 years than they would have before cutbacks were introduced.
The union is now calling for the complete elimination of remaining pay differences.
TUI President Seamus Lahart argued: "This two-tier pay regime is a cynical, damaging, discrimination, resulting in situations where colleagues are paid at different rates for carrying out the same work.
"We are not looking for preferential treatment for these teachers – we are simply looking for all teachers to be treated equally."
Mr Lahart added: "Needless to say, they are fully supported by longer-serving colleagues in this campaign for justice and equity, which remains TUI’s key priority."
The ballot will take place from mid-September to early October.
Earlier this year, Minister Joe McHugh told primary school teachers at the INTO conference that the issue of pay is 'unfinished business'.
However, he made no promises about when pay equality would be achieved - saying he couldn't commit to a timeline.
