Doncaster council has approved a 4% pay cut for all non-teaching staff, affecting 7,000 workers across the authority.
Unison, which organises local authority workers, is already planning a fightback. Branch secretary Jim Board said: "These plans mean a large number of our members are going to suffer quite a severe pay cut on top of an already falling standard of living.
"We are preparing a ballot and are recommending our members do not accept the pay cut. If they reject it and the council goes ahead then there is a very real threat of industrial action."