Swansea Council is racing to get staff agreement on its plans to transfer 73 members of its IT department to outsourcing supplier Capgemini on 1 October.
The council made assurances on pay and pensions last year after a two-month strike by IT staff, but the final terms of the transfer have yet to be signed.
"Staff will transfer to Capgemini on their current terms and conditions. The council and Capgemini have given a further commitment that terms and conditions will be protected for the 10-year life of the contract," said a council spokesman.
But Swansea IT staff will only know whether their pay will rise in line with local government pay next month, when the council finalises its contract with Capgemini. Employees are also worried about the future of their pensions.
The council said, "Staff will have the choice of remaining in the local government pension scheme or transferring to Capgemini's final salary scheme."
However, officials of IT workers union Unison are worried that transferred employees may lose their right to be members of the local government scheme if they spend less than 55% of their time on public sector work.
Unison regional officer Jeff Baker said the union would consider legal action or another dispute if matters were not resolved.