Public budgeting is a field of public administration and a discipline in the academic study thereof. Budgeting is characterized by its approaches, functions, formation, and type.
Authors Robert W. Smith and Thomas D. Lynch describe public budgeting through four perspectives. The politician sees the budget process as "a political event conducted in the political arena for political advantage". The economist views budgeting as a matter of allocating resources in terms of opportunity cost where allocating resources to one consumer takes resources away from another consumer. The role of the economist, therefore, is to provide decision makers with the best possible information. The accountant perspective focuses on the accountability value in budgeting which analyzes the amount budgeted to the actual expenditures thereby describing the "wisdom of the original policy". Smith and Lynch's public manager's perspective on a budget is a policy tool to describe the implementation of public policy. Further, they develop an operational definition:
A "budget" is a plan for the accomplishment of programs related to objectives and goals within a definite time period, including an estimate of resources required, together with an estimate of resources available, usually compared with one or more past periods and showing future requirements.
A brief note on Systems Theory applied to Political Science: Inputs enter the governmental system that produces outputs which—in turn—are related to outcomes. The conversion of inputs to outputs is a measure of efficiency as the measurement of contributing inputs to impacting outcomes is a measure of efficacy.
As a policy document, a government's budget is designed as a plan for implementing its policy. Traditionally, budgets served as a more rigid tool to implement policy in a retrospective setting. The functions associated with these values are listed under the Traditional Model and are control, management, and planning. The Modern Model, taking a less rigid approach, has replaced the control function with the monitoring function, the management function with the steering function, and the planning function with the strategic brokering function.
to the traditional control function, the monitoring function focuses on the consequences of expenditures.
Steering: as a response to the traditional management function, the steering function serves as a guide for managing.
Strategic Brokering uses the budget document as a means of constantly looking for possible directions and reacting to the environment.
Three values are generally discussed in the literature of public budgeting: accountability, efficiency, and efficacy.