More than 250 postal workers in the Isle of Man will receive ballot papers for strike action next week.
The Communication Workers' Union (CWU) is seeking a pay rise for its members but there has been a public sector pay freeze on the island.
Union members will have until 16 March to vote on whether to strike.
The union has said Isle of Man Post Office has refused to go to arbitration. However, the company has previously called for more talks.