The master's thesis examines the progress of the implementation of performance-based budgeting through the project planning process. Due to a rather pressing issue for any government, the main purpose of the survey is to find the reasons for the shortcomings and disadvantages. The research is therefore focused on analysing the current state and looking for good practices that would contribute to the further development of the field. Let us focus on the difficulties and factors that influence on slowing down the implementation of results-based budgeting in the Slovenian budgetary system. The first part of the survey is based on a survey method. The target audience was civil servants involved in the planning of projects in the development programming plan. The second part of the research is based on a study of national and international literature. The results of the analysis of the current situation have shown that the majority of respondents considered that the results achieved by the programme have no impact on the allocation of resources in budget planning and that a change in the procedures for planning, validating and recording projects would lead to more efficient spending and contribute to the overall objective of the sub-programme. Despite its shortcomings, the Republic of Slovenia ranks quite high in the OECD in terms of the level of existence and use of performance-based budgeting compared to other EU countries. Slovenia is in the "golden middle" of the ranking, still above the OECD average and among the leaders among developing countries. The key contribution of the master's thesis is the proposals and recommendations for improving the project planning process. The results of the research can serve as an operational tool for designing changes to the project planning process in the national budget. It is also a stimulus for decision-makers to think and act in processes that require inter-ministerial coordination, and a starting point for policy-making in the field of public finance. They offer optimisation of project planning processes and a change in budgetary mindset.