 2019  Contract number: [ complete ]  II.19. INVOICES, VALUE ADDED TAX AND E-INVOICING  II.19.1  Invoices and value added tax  II.19.2  E-invoicing  II.20. PRICE REVISION  Invoices must contain the contractor’s (or leader’s in the case of a joint tender) identification  data, the amount, the currency and the date, as well as the FWC reference and reference to the  specific contract. Invoices must indicate the place of taxation of the contractor (or leader in the case of a joint  tender) for value added tax (VAT) purposes and must specify separately amounts not including  VAT and amounts including VAT.  The contracting authority is exempt from all taxes and duties, including VAT, in accordance  with Articles 3 and 4 of the Protocol on the privileges and immunities of the European Union.  The contractor (or leader in the case of a joint tender) must complete the necessary formalities  with the relevant authorities to ensure that the supplies and services required for  implementation  of the FWC  are exempt from taxes and duties, including VAT.  If provided for in the special conditions, the contractor (or leader in the case of a joint tender)  submits invoices in electronic format if the conditions regarding electronic signature specified  by Directive 2006/112/EC on VAT are fulfilled, i.e. using a qualified electronic signature or  through electronic data interchange. Reception of invoices by standard format (pdf) or email is not accepted.  Should it not be possible to submit invoices as described due to circumstances beyond the  control of the parties, the Centre may temporarily allow submission of invoices in other formats.  Such submission shall only be permitted if prior approval has been granted in writing by the  Centre and if the invoice is submitted in an alternative format specified by the Centre.  If a price revision index is provided in Article I.5.2, this Article applies to it. Prices are fixed and not subject to revision during the first year of the FWC.  At the beginning of the second and every following year of the FWC, each price may be revised  upwards or downwards at the request of one of the parties.  A party may request a price revision in writing no later than three months before the anniversary  date of entry into force of the FWC. The other party must acknowledge the request within 14  days of receipt. At the anniversary date, the contracting authority must communicate the final index for the  month in which the request was received, or failing that, the last provisional index available for  33 