SIPTU's National Executive Council is due to make a decision this afternoon on whether to recommend acceptance or rejection of the national pay deal.
The country's largest trade union is expected to call on its members to vote in favour of the deal, having already argued that it was best possible outcome in the current circumstances.
However, the SIPTU leadership has expressed dismay at the Government's decision yesterday to impose a 1% income levy on all workers earning less than €100,100.
The union says the move will erode much of the pay increases negotiated by the social partners.
SIPTU's 250,000 members are due to begin voting on the pay deal tomorrow.