For assets and liabilities that shall be measured using the fair value concept, this concept is clearly determined through the respective IAS/IFRS standard applicable. However, the determination of the fair value, depending on the asset/liability to be measured and therefore the standard applicable, varied strongly within the discretionary leeway. In order to ensure a uniform and comparable usage across all IAS and IFRS standards, IFRS 13 standard was introduced and became effective as of January 1st, 2013. The standard defines fair value on the basis of the exit price notion and uses a fair value hierarchy, which results in a market-based, rather than entity-specific, measurement. As a consequence, for the income approach all inputs used to measure fair value have to be derived principally from a market participants point of view. The thesis aim is to identify the challenges and inaccuracies which arise when determining the relevant inputs for the income approach when taking into account the implementation of IFRS 13 standard. Furthermore it is the aim to demonstrate the valuation range resulting from diverging interpretations of the input parameters as well as the application of the varying methods of the income approach. The valuation range is calculated on the basis of a numerical simulation analysis. The first part of the thesis will define the term intangible asset, explain the regulations of IFRS 3 and IFRS 13 as well as the fair value concept, and present the underlying valuation approaches. Based on the income approach, subjective discretionary leeways implied in the determination of the fair value are demonstrated. The second part of the thesis analyzes how far the discretionary leeway leads to a conscious influencing of the valuation results by means of a numerical simulation analysis.