The ASTI teachers union says they will hold two separate ballots on industrial action.
The announcement follows today's meeting of the members' central executive council in Dublin.
Members will be balloted on industrial action, up to and including strike action, over new teachers' pay. If teachers vote in favour of strike action it could result in school closures this autumn.
The union represents 18,000 teachers - more than half of all second-level teachers.
Teachers who entered the profession after 2010 are on different pay scales than their colleagues even though they may carry out the same duties and responsibilities.
In a separate ballot which relates to measures applied to ASTI members following their rejection of the Lansdowne Road Agreement, members will be asked to vote on withdrawal from supervision and substitution duties.
The union is recommending that members vote in favour of industrial action over both of the issues.