Mothers and pregnant women face losses of up to nearly €3,000 a year as part of the tax on maternity benefit which came into force on July 1st.
Women’s representatives said the measure was a mean-spirited move by the Government.
The tax will contribute €15m to the exchequer in 2013, and €40m per full year from then on.
But the National Women’s Council yesterday expressed concern that many women were not aware when the reductions in benefit would take affect.
Its policy advisor Ann Irwin explained: “It’s a very mean-spirited move in a lot of ways. Even the commission on taxation has said that maternity benefit should remain outside the tax net. It’s there for mothers to nurture children when outside the workforce.
“The benefit payments are an important acknowledgment for mothers of the cost of having a baby in Ireland.”
Opposition parties have branded the new tax measure as “anti-family” and it could see working mothers pay up to €2,700. Mothers will pay different rates depending on their top-up payments from their employer as well as assessments on their means.
The tax could see benefits reduced by up to €103 a week, the council said.
The Department of Social Protection paid out €309m in maternity benefit payments in 2011.
Mothers get between €217.80 and €260 a week in payments for 26 weeks.
The council said women who got employer top-up payments would be worst affected but that it remained unknown how many would be affected by the levy.
But ministers have insisted women overall will not be worse off. Some had been receiving high payments while on maternity leave, ministers have also said.
However, Ms Irwin said many women remained in the dark about the tax. “The first they may know about it while on leave is when their next pay package comes in.”