Wigan drug and alcohol support employees will down tools for a one-day strike later this month in a pay dispute.
A total of 31 staff employed by Addaction will take part in the industrial action on Friday August 23.
Trade union Unison says the organisation has failed to honour a promise to pay NHS rates for the job, costing some employees as much as £1,000 over the course of the three-year pay deal.
The employees provide services commissioned by Wigan Council and were previously directly working for the health service.
However, Addaction is now digging its heels in over a nationally-agreed pay rise for NHS staff.
The strike notice follows an overwhelming vote for industrial action, with all respondents to the ballot voting to strike and a turnout of well over 80 per cent recorded.
Katherine Herbert, a drug and alcohol worker and Unison rep, said: “We all work very hard to provide a good service. It is important work and it’s great when we make a difference for people and help them to turn their lives around.
“We used to be employed directly by the NHS, but now that Addaction has taken over our pay is falling behind the NHS rates. We feel undervalued and it is getting harder for us just to pay the bills.
“I never imagined that we would have to go on strike, but we are desperate now and determined that we should be paid the right rate.”
Unison said the strike action could still be averted if Addaction backs down and agrees to match NHS salaries for its staff.
Unison North West regional organiser Paddy Cleary said: “Addaction promised staff they would be paid the NHS rates, but they have gone back on their word.
“Our members’ living standards have been hit and they are upset that they have been misled by Addaction. All the staff who are performing this valuable work should be paid the proper rate for the job.
“Addaction also turned down the opportunity to access funding made available by the Department of Health and Social Care, which was set aside specifically so non-NHS organisations such as Addaction could afford to implement the Agenda for Change pay deal.
“The employer was aware of its obligations to pay the public sector rate for the job when it took on the contract to deliver this public service. It has wilfully neglected its obligations and has left its staff out of pocket and out of patience.
“It’s not too late to avert a strike. Addaction needs to act now and honour the promise made to this group of staff.”