Running a business activity is burdened by high risk. This follows from the lack of being cautious when choosing business partners. The Ministry of Finance, when defining due diligence, draws attention to possible threats following from the selection of a new contractor, as well as continuation of previous cooperation with existing contractors. Lack of due diligence in domestic transactions may result in unconscious participation in tax frauds. Hence, it is necessary to have open access to databases and official registers containing e.g. register data of a taxpayer, a status as a VAT tax payer, concessions held and business licenses. Modern administration, including tax administration, emphasises openness and accessibility to information about companies and business entities. The solutions adopted and the scope of presented information in individual European countries differ significantly. Some of European tax administrations enable to verify a contractor as a reliable in terms of meeting tax obligations. The aim of this article is to indicate appropriateness of using online official lists and registers of entrepreneurs to verify contractors, which is important with regards to reducing a business risk of a business activity.