Credit Union Australia staff will have their access to annual leave restricted during the first five months of next year as the organisation trains almost 800 staff in how to use a new core banking computer system currently under development.The leave freeze, which the Finance Sector Union argues is unreasonable, is slated to last from January to May 2013.Dawn Tsoubos, general manager of human resources for CUA, said the organisation was working with the FSU, and that it had yet to lock down a training schedule, but had announced the freeze in order to give employees a "heads-up" that they might find it easier to take holidays outside of that five-month period.Tsoubos said that CUA was prepared to look at applications from people who "need to take leave and have extenuating circumstances" but that the leave freeze was intended to make sure people were available to attend training programs, and to ensure all hands were on deck when the new computer system is turned on.CUA selected Tata Consultancy Services' BaNCS as the basis for its new core banking system in March 2011, which was described at the time as being a two-year project. Last October it announced that it had also signed with TCS for the BaNCS online banking system. The new system will replace a system developed largely in-house by the credit union and its predecessors.Dubbed "Project Nucleus" inside CUA, Tsoubos said the core banking program was going "extremely well", with implementation scheduled to begin in the first half of next year.  Banking Day, however, has heard suggestions that the project is running several months behind schedule.To minimise the potential for disruption to either staff or customers, Tsoubos said it was important to have a very robust training plan for the 80 per cent of CUA's 950 employees who will have to use the system.