All five project workers at a St Mungo's hostel for homeless people will go on strike over Christmas for the second time in a month in a dispute about pay and conditions.
The strike, at the 17-bed North Herts Sanctuary hostel in Hitchin, Herfordshire, will run from 22 December to 3 January and follows a week of industrial action which began on 30 November.
The union Unite said St Mungo's had reneged on a promise to transfer the five hostel staff onto its terms and conditions after it took over the running of the hostel in 2011.
Unite argued that it would cost St Mungo’s less than £5,000 a year to align the terms of the hostel workers with the more generous terms of the charity.
The staff used to work for the North Herts Sanctuary charity before St Mungo's took over the management of the service and kept their existing pay and employment terms when they transferred.
Unite said that St Mungo's had said the staff could move onto its terms and conditions but later said they must first pass a capability test.
A spokeswoman for St Mungo's said: "St Mungo's usual process to move transferred-in staff onto St Mungo's terms includes a suitability interview against our job roles and person specifications."
Unite's regional officer, Nicky Marcus, said: "The management of St Mungo’s refuses to recognise the need to align the pay and conditions of the project workers with the rest of the charity’s workforce, as was previously promised. The total cost of this exercise would be just £5,000 a year.
"Our members in Hitchin are receiving less pay and working more hours than other staff doing the same jobs in St Mungo’s."
Elizabeth Harper, regional director at St Mungo’s, said the organisation had retained the pay and employment terms of the staff when they transferred and had offered them a fair process to transfer onto its pay and terms.
"This is not about the additional costs, which St Mungo’s would be willing to cover, but about a fair and consistent treatment for all our staff," she said.
"Our first priority, as ever, will be ensuring that anyone using the hostel receives the best support we can offer, especially during the cold winter period."
A sixth person, who used to work at the hostel, has accepted a job elsewhere at St Mungo's.