The achievement of any project depends on the completion of project within specified time period and estimated cost. Hence this study aims to explore cost overrun factors from the aspect of civil workers in Tamil Nadu. A total of 500 civil workers were contacted and questionnaires were self administered to those civil workers for obtaining responses. Out of 500 samples, 460 samples were taken for further analysis after eliminating the response bias. Civil workers stated that the most of the projects gets delayed due to cost overrun issues. Here in this study, factors affecting cost overrun are material related factors, machinery related factors, money or finance related factors, manpower related factors, project management and contract administration related factors, and information and communication related factors. © 2020 SERSC.