Case C-4/20: Judgment of the Court (First Chamber) of 20 May 2021 (request for a preliminary ruling from the Varhoven administrativen sad — Bulgaria) — ‘ALTI’ OOD v Direktor na Direktsia ‘Obzhalvane i danachno-osiguritelna praktika’ Plovdiv pri Tsentralno upravlenie na Natsionalnata agentsia za prihodite (Reference for a preliminary ruling — Taxation — Common system of value added tax (VAT) — Directive 2006/112/EC — Article 205 — Persons liable for payment of VAT to the public exchequer — Joint and several liability of the recipient of a taxable supply which has exercised its right to deduct VAT knowing that the person liable for payment of that tax would not pay it — Obligation of such a recipient to pay the VAT not paid by the person liable for payment and the default interest due on account of that person’s failure to pay the VAT)