(a)

In the light of the principle of proportionality, which is a general principle of European Union law, is a provision of national law permissible, such as that established in Article 18 of the VAT Law, under which, inter alia, tax on the supply of immovable property effected through enforcement in respect of goods owned by the debtor or in his possession in breach of existing law is calculated, collected and paid by a court enforcement officer carrying out an enforcement action who, as paying agent, bears liability in the event of failure to fulfil that obligation?

(b)

In the light of Articles 206, 250 and 252 of the directive and of the principle of neutrality arising therefrom, is a provision of national law permissible, such as that established in Article 18 of the VAT Law, under which a paying agent as referred to in that provision is required to calculate, collect and pay, within the tax period of the taxable person, an amount of value added tax on a supply, effected through enforcement, of goods owned by that taxable person or in his possession in breach of the law in force, in an amount comprising the product of the proceeds from the sale of the goods, minus value added tax and the applicable rate of that tax, with no reduction of that amount by the amount of input tax from the beginning of the tax period to the date of the collection of that tax from the taxable person?