An initial small-scale benchmarking survey conducted by Oxfam found that charity workers south of the border were paid between 20 and 25 per cent more.
The first full salary survey in the Republic of Ireland is to be conducted by The Wheel, the Irish umbrella body for community and voluntary organisations.
It will send 1,800 surveys to 12,000 organisations in January, and the study is expected to be completed by April.
"There is no salary survey of the voluntary sector in Ireland," said Deirdre Garvey, chief executive of The Wheel. "It is long overdue and badly needed."