In public organizations, depending on the economic climate of the country, such as recession or economic prosperity, the allocated budget varies. In such conditions, these organizations face the problem of defining the types of development projects outsourcing and determining the appropriate method of payment to contractors is critical. because the lack of proper management in the amount and time of budget expenditures can impose costs on the organization beyond expectations. In this study, recession, equilibrium and economic prosperity, is considered an effective factor in budget allocation. Therefore, for cost minimization and risk coverage, we present a robust scenario-based optimization model that incorporates the completion times, expediting costs, delay penalties and budget uncertainties to evaluate internal resources and available contractors for conducting the project and to determine the optimal solution and payment scheduling that minimizes the total cost. The slight difference between the maximum and minimum response stability under different management attitudes indicates the effectiveness of the proposed approach. Our results demonstrate that when the project completion time is promoted and there are no considerations for quality and technical knowledge, it is necessary to issue outsourcing allowance and the activities should be designed in a manner that they can be outsourced.