About 70 health visitors are to stage a near month-long strike in a continuing dispute over pay and standards.
The strike by members of Unite at Lincolnshire County Council is due to start on 18 November and continue until 13 December.
The union said workers were significantly worse off since being transferred from the NHS in 2017.
The authority said it had increased pay for workers "in line and above health service workers".
According to the union, some workers stood to lose £150,000 over the duration of their careers due to a two-tier grading system introduced by the authority.
This, it said, discriminated against some staff by placing them in the lower pay band and limiting their chances of progression, despite them having the same qualifications as those in the higher tier.
Steve Syson, regional officer for the union, said workers stuck in the lower tier would be £4,000 worse off a year.
"Now is the time for the council to come to the table to resolve this dispute once and for all before the strike begins," he said.
He added the council was already "haemorrhaging health visitors", with 20 leaving or about to leave since action began in the summer.
Heather Sandy, interim director of education at the council, said: "It is disappointing that despite constructive discussions with representatives from Unite, this industrial action is being pursued.
"The council's career progression scheme, which opened in October, means no staff member has to remain on a static salary - all can move on in their careers and be financially rewarded beyond that available in the NHS."