Budgetary institutions encompass two different types of institutional arrangements: fiscal rules and budget process rules. Fiscal rules entail substantive constraints on public spending, taxation, deficit and debt, usually in the form of explicit quantitative targets. Budget process rules, in turn, entail procedural aspects of public budgeting: they establish the competencies of the actors involved in the budget process and outline the procedures that govern the preparation, adoption and implementation of the budget. This entry gives an overview of the different forms and characteristics of these institutions and also of their impact on budgetary outcomes.