With the article “Clausola penale e imposta di registro: la causa della disposizione determina il regime fiscale,” published on Corriere Tributario (no. 3/2024), Giuliano Foglia and Maddalena Cecci comment on the first judgement given by the Supreme Court regarding the tax regime of penalty clauses included in contracts, retracing the agreeable reasoning that the ancillary nature and essentially compensatory cause that the penalty clause fulfills implies that the contract in which it is included is subject to single taxation under Article 21(2) TUR, as if the deed contained a single provision.