According to the CJEU, the VAT exemption of Article 135(1)(j) of the VAT Directive for the supply of a building or part thereof and of the associated land, with the exception of the supply that is made before the first occupation, also applies to the supply of a building the first occupation of which took place before its conversion, even if the Member State concerned has not laid down in its national law the conditions for applying the criterion of first occupation to the conversion of buildings, as it of Article 12 paragraphs 1 and 2 of the VAT Directive could have done.
Source BTW jurisprudentie
See also C-239/22 (Belgian State and Promo 54) – Judgment – Condition of the first use of a building
