In accordance with the judgment of the Court of Justice of 13 March 2014, Firin, (C-107/13), is the deduction of input tax on a payment on account excluded where the occurrence of the chargeable event is uncertain at the time when the payment on account is made. Is that exclusion determined by reference to the objective situation or by reference to the point of view of the person having made the payment on account in the light of the circumstances objectively apparent to him?