Opinion of Advocate General Kokott delivered on 15 October 2020.#European Commission v Hungary.#Appeal – Article 107(1) TFEU – State aid – Hungarian tax on turnover linked to advertisements – Information used to determine the reference system – Progressivity of tax rates – Transitional measure for the partial deductibility of losses carried forward – Existence of a selective advantage – Burden of proof.#Case C-596/19 P.