Heath visitors in Lincolnshire have begun a near month-long strike in a dispute over pay and conditions.
About 70 members of the Unite union at Lincolnshire County Council are due to strike until 13 December.
The union said some workers were "significantly worse off" since being transferred from the NHS in 2017.
The council said it had held constructive discussions with union officials and was disappointed the action was being pursued.
According to the union, some workers stood to lose £150,000 during their careers due to a two-tier grading system introduced by the authority.
It said some staff were being placed in the lower band despite them having the same qualifications as those in the higher tier.
Steve Syson, regional officer for the union, said: "We need to keep up the pressure on the authority to achieve the proper grade 10 role for all the health visitors who have the same qualifications."
"The situation is serious as the council is haemorrhaging health visitors who are leaving for better paid positions elsewhere."
The walkout follows six days of strike action in July when campaigners protested outside the county council headquarters.
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."
According to the Local Democracy Reporting Service, Unite represents 76 of the 126 health visitors employed by the council.