In this paper, the authors explore the central tenets behind automated valuation models (AVMs) and professional auditing, reconcile them, and aim to provide a solid framework upon which auditors can make their case when auditing AVMs. More specifically, we present a mass valuation model for the Finnish residential property market used by Orava Residential REIT and its annual auditing process conducted by Realia Management Oy. Emphasis is given to the auditing process.Despite their long methodological history (Hotelling 1931, Rosen 1974), automated valuation models have been used by Real Estate professionals for a relatively short while, only gaining traction with the advent of digitisation. Currently, these methods are primarily used for taxation and mortgage evaluation purposes and their use in defining fair value is less common. According to the international accounting standard IFRS 13, a company must value investment properties to IFRS fair value. The company management is ultimately responsible for defining fair values.The use of AVMs in fair value definition requires external opinion of values and inspection of in-house modelling due to investor demand and local legislation. The combination of increasingly advanced valuation tools and growing popularity of new real estate investments ownership structures that allows for easy investment by real estate non-professionals creates additional transparency needs. These needs are fulfilled by external auditing which tests the validity of the assumptions, the data and the models and processes that were employed in the use of the valuation tools. Auditing quality is maintained by organisations such as the Auditing Standards Board and the International Organisation of Standards. However, outside accounting and certification audits, a relative freedom exists. In auditing AVMs, task-specific tools, such as guidance notes are either missing or are still under development (RICS, IVS).Orava Residential REIT solely uses its in-house, multivariate regression model for determining fair values in quarterly and annual financial reporting. This model is presented in the first section of the paper. In the second section the annual auditing process of Orava AVM is explained in detail. In the third and last part, the authors discuss the best practices of auditing while exploring and taking into account nuances that relate specifically to real estate valuation and automated value estimation models.