Probabilistic assessment of existing structures can be a powerful tool for efficiently prioritizing the necessity of maintenance interventions within usually limited budgets available for this activity of ever increasing importance – spend the limited money where it is the most effective. However, structural engineers in practice usually have neither sufficient know-how nor enough time at hand to apply full- or semi-probabilistic procedures in their daily structural assessment work. They need an easily applicable deterministic evaluation tool to judge what level of structural safety deficit is still acceptable if recommending disproportionate (structural) interventions shall be avoided. Based on semi-probabilistic updating methods, further considering generally accepted reliability indexes and proportionality of maintenance interventions, a simplified proposal for acceptable structural safety deficits in deterministic assessments of existing concrete structural elements is derived and discussed. Varying material qualities, as possibly encountered in existing structures, and different types of potentially governing failure modes are considered, in order to link deterministic degrees of compliance (that is, inverse of “unity checks” as applied elsewhere) to reliability indexes which, in turn, are related to efficiency of maintenance interventions and the need for urgent safety measures. These reflections are applied, on the one hand, in combination with directives for new structures and, on the other, with prescriptions for the assessment of existing structures, considering information provided in Swiss codes.