||During the past few years there have been many changes in financial reporting rules in EU countries. One significant change from the real estate point of view has taken place in balance sheet, where property investment account is switched to the asset side of the balance sheet, separate from the property, plant and equipment. Since 2005, all companies listed in the stock market, have the obligation to apply International Accounting Standards/International Financial Reporting Standards (IAS/IFRS) in their everyday practice. At the same time, more and more researchers have pointed to the problem of valuation accuracy and to the uncertainty of the valuation product. Since the behavioural finance theory has came along, the researches about the influence of the behaviour of appraisers to their valuation estimation has emerged to the field. Although plenty of work has been done in this area, it is still unclear what factors play the most significant role in making the valuation uncertain. The aim of the paper is two-sided – firstly, to point out the practical problems in implementing the income approach in valuation for financial reporting purposes in Estonia and secondly, to bring out behavioural aspects in valuation process within the Estonian appraisers. There is an intention to conduct an experimental valuation case study among all 42 certified general appraisers in Estonia to achieve the aim of the paper. The main research question is, how and to what extent does the appraisers' behaviour influence their implementation of income approach in estimating the market value of commercial real estate for financial reporting purposes?