BUS Eireann will implement changes to the terms and conditions of its workers from Sunday week unless trade unions come up with alternative savings.
Transport Minister Leo Varadkar told the Dail that the company "could not postpone" the cost-cutting measures any longer, as talks with unions had been ongoing for 11 months.
His comments came as Bus Eireann staff plan to ballot for industrial action after the firm said it planned to cut holiday entitlements and reduce overtime and premium payments as part of efforts to save €9m a year. A further €11m will be saved from operations.
Mr Varadkar said "no progress" had been made on the proposed cuts and that despite talks with the Labour Relations Commission, alternative savings had not been identified.
The cuts were approved by the Labour Court last February, which noted the company was in a difficult financial position and, unless payroll savings are made, jobs could be at risk.
"Bus Eireann has accumulated losses of €27m in the last five years, a position which is unsustainable and places the viability of the company at risk," Mr Varadkar said.
"Although much of the operational savings have been delivered, no progress has been made on savings from terms and conditions despite the involvement of the Labour Relations Commission and the Labour Court in the process.
"Now, 11 months after deliberations started and three months after the Labour Court recommendation was issued, the company simply can't postpone the implementation any longer.
"I'm assured that it will engage with the unions at any time to discuss alternative approaches, but until and unless these are agreed, the May 12 implementation must proceed."
If the savings are not made, the firm faces annual losses of €11m.
Mr Varadkar added that the loss-making Expressway services could be under threat if the savings were not made.
"I very much hope that management and unions use the period until May 12 to engage in further dialogue which can ensure that the necessary savings are introduced and the provision of bus services for the public are protected," he added.