Case C-868/19: Judgment of the Court (Seventh Chamber) of 15 April 2021 (request for a preliminary ruling from the Finanzgericht Berlin-Brandenburg — Germany) — M-GmbH v Finanzamt für Körperschaften (Reference for a preliminary ruling — Value-added tax (VAT) — Directive 2006/112/EC — Article 9 — Taxable persons — Article 11 — Option for the Member States to treat as a single taxable person persons who are independent from a legal point of view but are closely linked to one another financially, economically and organisationally (‘VAT group’) — Concept of ‘close financial links’ — National legislation according to which partnerships, whose partners, alongside the controlling company, are not solely financially integrated persons in the undertaking of the controlling company, are prevented from being a member of a VAT group — Legal certainty — Preventative measures against fraud and tax evasion — Proportionality — VAT neutrality)