Article 21 -

1. If an invoice is issued or payment made for Goods or Services prior to the effective date of this Law or prior to the registration date, and the Supply takes place after this date, then Tax shall be due on the date of Supply.

2. The provision of paragraph (1) of this article applies to Internal Supplies between a taxable Supplier residing in the Kingdom and a Customer in another Member State or vice versa.

3. In relation to continuous Supplies that are partially made prior to the effective date of this Law or the registration date, and partially made after this date, Tax shall not be due on the portion made prior to the effective date or the registration.