Section 18(1) b) of Act. No. II of 2007 on the entry and stay of third country nationals shall be construed so that in case in proceedings instituted for the acquisition or prolongation of a third country national’s entitlement to stay the third country national submits false data or untrue fact, he shall bear the legal consequences of such conduct. Where the entitlement to stay is sought for the purpose of carrying out income-earning activities, sustenance capability can be proved by lawful (taxed) income deriving from lawful income-earning activities. The submission of false data or untrue fact is committed when the data or fact is submitted. The immigration authority shall satisfy itself of the falseness of the data and/or the untrueness of the fact submitted. Section 18(1) b) of the said Act prescribes the mandatory application of the legal consequences (denial, withdrawal), hence the authority shall have no margin of appreciation.