You won't know, the use of contract is to give the agency the upper hand and flexibility to manage headcounts. Depending on agency, the usual practice is you need to be probated for 1 year before emplacement but varies across contracts. My department practice (from my observation lah) is to extend people's probation (even the high performers on contract) to squeeze even more out of these people and see their true potential. Unfortunately sometimes it is being used by the managers to get rid of staffs they do not like by failing their performance reviews.