The Civil Public and Services Union (CPSU) is warning that its members will not make up a savings shortfall by the HSE.
Reports this weekend claim the HSE will most likely fail to meet €290m worth of cuts agreed under the Haddington Road deal.
According to The Irish Times a confidential consultancy report shows the final budget may be out by as much as €200m.
The CPSU, which represents lower paid civil servants, held its annual conference in Galway this weekend.