The Irish Nurses and Midwives Organisation has denied they are industrial action looking for a pay rise.
The nursing union is to begin a work to rule on March 7, with rolling closures to follow at acute hospitals.
It maintain's next month's industrial action is over staffing levels.
But General Secretary Liam Doran admits it could come down to finances: "The key demand, lets be quite clear, is measures that will attract and retain nurses and midwives.
"If you can't get them in on current arrangements we are talking about more money but we are not seeking a pay claim."