This work organizes the standards and procedures for user financing of Public Private Partnerships (PPPs) within the debate on government task fulfillment and the type of privatization, before examining specific areas of a New Public Private Partnership (NPPP) and determining the legal framework of NPPP models. It concerns a public law contract. A budgetary classification of the models is carried out to subsequently examine improvements in the fee collection process based on previous experiences in road construction. In a private law arrangement of the user relationship between the private partner and the private user, the principles of public financial management or even fundamental rights must be considered as benchmarks in this relationship. Following this, a four-stage examination is proposed to assess the appropriateness of a user fee, with the issue of appropriateness being entrusted to a regulatory authority.