Property tax is a main source of local authority and contributes to nation’s development. Local Government Act 1976 (Act 171) has authorized local authority as the responsible party in levying property tax. Based on pilot study, there is an urgency in conducting property tax reassessment due to the lack of manpower in valuation department. Besides, it was found that the outsource solution by appointing private valuation firm also failed to complete the reassessment within dateline. Hence, this study is conducted to scrutinize the most significant factors that cause failure in completing reassessment work among private valuation firm appointed by local authority. Questionnaires were distributed among local authority within Iskandar region to rank the most important factors that cause the failure. The results shows that workload increase, and time constraint is the most prominent factors that cause failure in completing the reassessment work. This paper is significant for local authority in handling the problem regarding reassessment work among appointed valuation firm.