When speaking about the liabilities of companies it is important to emphasise that company members are, by legal regulations, exempted from the liability for a company’s obligations. The reason for this is that companies have their legal personality recognised by positive legal system which is separated from the personalities of their members, physical or legal entities, and which means that when a company establishes contractual relationship in legal dealings, the obligation is in any case assumed by the company itself, and only under certain legally defined conditions by its members as well. Exactly this legal regulation has left enough room for frequent abuse of rights at the expense of creditors. When following debt collection procedures with its taxpayers, a tax authority, as a creditor, frequently faces various forms of abuse of such legal regulation. For this reason, the novel of the General Tax Act from 2012. extended the circle of tax guarantors to company members as well, in the procedure of establishing the abuse of rights, that is, through the institution of „Piercing the Corporate Vei“. By this institution, the separation of companies and members is abolished, which implies that if the procedure of the abuse of rights establishes that there has been one, the liability for the obligations from taxation-debtor relationship as tax guarantors shall be assumed by, besides the head debtor (the company), company members as well, that is, the members of the board, company’s executive officers and the persons related to them. This paper describes the procedure of establishing the abuse of rights in the taxation procedure, as well as the prerequisites which need to be met in order to initiate the procedure in the first place. The relevant resources of legal regulations for this matter is principally the General Tax Act and Croatian Companies Act, and the very procedure and prerequisites which need to be met are elaborated in detail by the Methodology of establishing the abuse of rights in a tax system.