The abbreviation HOAI stands for "Fee Scale for Architects and Engineers" (Honorarordnung für Architekten und Ingenieure) and regulates the fees for architectural and engineering services in Germany. In order to be able to evaluate the architectural and engineering services as precisely as possible, the HOAI divides them into service phases.
The fees for the individual service profiles, such as buildings or interiors, are specified in the HOAI's fee tables as "from-to" values, which corresponds to the minimum and maximum values. However, the HOAI is not binding, but only serves as a guideline for the remuneration of architects and engineers.