Digitalisation tremendously affects the basic idea of value-added taxation: the exchange of goods and services for consumption. This dissertation focuses on the exchange of seemingly "free" online services and the customers' consent to the exploitation of their personal data. Such exchanges can be subject to VAT, and the taxable amount must be calculated according to suppliers' costs. The results are based on a structural analysis of EU VAT as a tax on consumption compared to other theoretical consumption models. Additionally, other digital business models, such as the Sharing Economy or Bitcoins, can also be subsumed under the idea of EU VAT as a tax on consumption.