Up to 500 SIPTU home help workers will be balloted for strike action early in the new year.
The staff are working in community and disability services across Dublin city and county.
The union claims some Section 39 organisations have failed to honour a national pay restoration agreement for home help staff.
SIPTU health division organiser Paul Bell said union representatives have "done everything possible" to secure payments following a WRC deal brokered in April.
He said: "Our members in these organisations, all low paid workers, are falling further behind, having endured cuts in pay of approximately 6% and also suffering a cut in their hours which has had a knock on effect on service users and their families.
"They now have been left with no option other than to take action.”
Mr Bell also said Section 39 workers in health and social care organisations that have not yet committed to pay restorations will also be balloted for strike action in January.
He suggested: “These organisations, approximately 250 in total, will be balloted for strike action by SIPTU and other trade unions involved in this dispute, around the third week of January.
"These organisation are located in every corner of the country and many are household names in the provision of health and social services.”
Section 39 employees in state-funded voluntary agencies are not technically considered public servants.
However, the workers are seeking full pay restoration after taking a cut along with public servants during the economic crisis.
