The construction of public buildings plays an important role in the Brazilian construction market.However, it is necessary the inclusion of companies that active on this market in a competitive bidding process for the construction of these buildings, which is strategically and economically important for those companies.Therefore, the accuracy in determining the costs of this management process is extremely important for any organization to control the bidding process, generating important information for decision-making.However, for their productive characteristics and various indirect costs involved in the construction process, there is great difficulty in controlling and allocating these costs.This paper deals with the application of activity-based costing (ABC costing) in the budgets process of a company that operates in the execution of public buildings sector.This study describes the implementation process, and makes the critical analyze of the results, comparing the ABC costing methodology and traditional costing system.