Staff members, irrespective of their category (A, B, C or L), are usually appointed for an initial period of four years, subject to a satisfactory probationary period of six months.
Extensions for staff of all categories are for an indefinite period. For staff with an indefinite contract, the contract terminates at the end of the month in which the staff member turns 63 if recruited after 1 July 2010.
Some ESA staff positions are referred to as Advance Recruitments. Contracts for advance recruits are for a maximum of two years and are not renewable. However, upon termination of an advance recruit contract an ESA staff contract may be given.