Participatory budgeting has become a popular application of e-participation in Germany. About one hundred local governments have executed participatory budgets in the last year. Citizen participation in public budget planning is not formally requested by law in Germany. Also, the legal procedures to settle the budget of a local governments are not defined in detail. In consequence, different procedures exist, which lead also to different implementations of procedures in participatory budgeting. In this contribution, process models for (participatory) budgeting are investigated and a reference process model for traditional budget planning and online participatory budgeting is developed. Reference process models support cities and municipalities to assess the added value and to estimate the human and financial resources to execute participatory budgeting. Hence, comprehensive reference process models are helpful instruments for local governments to decide whether to perform participatory budgeting or not. They are also contributing to successful e-participation endeavors by providing conceptual models (blueprints) for scoping the activities to engage with citizens from the beginning of planning till the evaluation of impact and outcomes.