Case C-717/19: Judgment of the Court (Seventh Chamber) of 6 October 2021 (request for a preliminary ruling from the Fővárosi Törvényszék — Hungary) — Boehringer Ingelheim RCV GmbH & Co. KG Magyarországi Fióktelepe v Nemzeti Adó- és Vámhivatal Fellebbviteli Igazgatósága (Reference for a preliminary ruling — Value added tax (VAT) — Directive 2006/112/EC — Article 90(1) — Reduction of the taxable amount where the price is reduced after the supply takes place — Payments made by a pharmaceutical company to the State health insurance agency — Article 273 — Administrative formalities required by national legislation for the exercise of the right to reduction — Principles of fiscal neutrality and proportionality)