1.

must be interpreted as not precluding legislation of a Member State which provides for a limitation period to apply for a value added tax (VAT) refund resulting from a reduction in the taxable amount of VAT in the event of total or partial non-payment, the expiry of which results in penalising an insufficiently diligent taxable person, provided that that limitation period only begins to run from the date on which that taxable person was able, without showing a lack of diligence, to assert its right to a reduction. In the absence of national provisions concerning the rules governing the exercise of that right, the starting point for such a limitation period must be identifiable by the taxable person with a reasonable degree of probability.

2.

must be interpreted as precluding, in the absence of specific national provisions, a requirement on the part of the tax authority which renders the reduction in the taxable amount of value added tax (VAT), in the event of total or partial non-payment of an invoice issued by a taxable person, subject to the condition that that taxable person corrects the initial invoice beforehand and that it communicates beforehand to its debtor its intention to cancel the VAT, where it is impossible for that taxable person to make such an adjustment in due time, for reasons beyond its control.

3.