citizenship of the Union from being obtained again, is compatible, from the point of view of EU law, with the principle of proportionality, having regard to the consequences of such a decision on the situation of the person concerned. That court considers that it would be logical, in that case, for such a review of proportionality to be required and asks, in the present case, whether the mere fact that JY has renounced her citizenship of the Union by putting an end herself to the special relationship of solidarity and good faith which united her to Estonia and also the reciprocity of rights and duties with that Member State, which formed the bedrock of the bond of nationality (see, to that effect, judgment of 12 March 2019, Tjebbes and Others (C‑221/17, EU:C:2019:189, paragraph 33), is decisive in that regard. 28 In those circumstances, the Verwaltungsgerichtshof (Supreme Administrative Court) decided to stay the proceedings and to refer the following questions to the Court of Justice for a preliminary ruling: ‘(1) Does the situation of a natural person who, like the appellant in cassation in the main proceedings, has renounced her only nationality of a Member State of the European Union, and thus her citizenship of the Union, in order to obtain the nationality of another Member State, having been given a guarantee by the other Member State of grant of the nationality applied for, and whose possibility of recovering citizenship of the Union is subsequently eliminated by revocation of that guarantee, fall, by reason of its nature and its consequences, within the scope of EU law, such that regard must be had to EU law when revoking the guarantee of grant of citizenship? If the first question is answered in the affirmative, (2) Is it for the competent national authorities, including any national courts, involved in the decision to revoke the guarantee of grant of nationality of the Member States, to establish whether the revocation of the guarantee that prevented the recovery of citizenship of the Union is compatible with the principle of proportionality from the point of view of EU law in terms of its consequences for the situation of the person concerned?’ Consideration of the questions referred The first question 29 By its first question, the referring court asks, in essence, whether the situation of a person who, having the nationality of one Member State only, renounces that nationality and loses, as a result, his or her status of citizen of the Union, with a view to obtaining the nationality of another Member State, following the assurance given by the authorities of the latter Member State that he or she will be granted that nationality, falls, by reason of its nature and its consequences, within the scope of EU law where that assurance is revoked with the effect of preventing that person from recovering the status of citizen of the Union. 30 It should be noted at the outset that, in accordance with Paragraph 20(1) of the StbG, a foreign national who satisfies the conditions laid down in that provision is to be given the assurance that he or she would be granted Austrian nationality if, within two years, he or she provides proof of having relinquished the citizenship of his or her State of origin. It follows that, in the naturalisation procedure, the grant of Austrian nationality to that foreign national, following such assurance, requires, as a precondition, the loss of his or her previous nationality. 31 Consequently, as a first step, the – at least temporary – loss of the status of citizen of the Union of a person, such as JY, who holds only the nationality of his or her Member State of origin and starts a naturalisation procedure in order to obtain Austrian nationality, stems directly from the fact that, at the request of that person, the government of the Member State of origin has dissolved the bond of nationality with that person. 32 It is only as a second step that the decision of the Austrian authorities with jurisdiction to revoke the assurance as to the grant of Austrian nationality entails the permanent loss of the status of citizen of the Union of such a person.