The contractor (or leader in case of a joint tender) must complete the necessary formalities with the relevant authorities to ensure that the supplies and/or services required for implementation of the FWC are exempt from taxes and duties, including VAT. 

The contractor shall have sole responsibility for compliance with the tax laws which apply to him. Failure to comply shall make the relevant invoices invalid. 

## II.18.2. E-invoicing 

In accordance with the provisions of Annex XVII, the contractor (or leader in 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 e-mail is not accepted. 

## II.19. PRICE REVISION 

If Article Error! Reference source not found. refers to a formula governing price revision, then the provisions set out in this Article apply. 

## II.19.1. Yearly price revision 

The parties agree that the prices shall be subject to a yearly price revision according to the provisions set out below. 

## II.19.2. Date of effect of the yearly price revision 

Price revisions shall always be applicable as of 1$^{st}$ January. For a FWC signed during calendar year N, the first price revision shall be calculated as set out below during year N+1 and become applicable as of 1$^{st}$ January of year N+2. 

However, when a product or service was not included in a FWC from the beginning, but introduced through an amendment signed in year O, otherwise than as a result of a change request, the first price revision for that product or service shall be calculated during year O+1 and become applicable as of 1$^{st }$January of year O+2. 

As regards hardware, complex and other than complex hardware, and unless otherwise agreed by the parties, when a product is introduced into the FWC through an amendment signed in year P as a result of a change request after the procedure set out in Article II.19.3 below has been initiated, the new product shall bear the price of the product it replaces, i.e. the non-revised price for the remainder of year P, and the revised price as of 1$^{st}$ January of year P+1. 

## II.19.3. Procedure for calculating the yearly price revision 

Between 1$^{st}$ July and 30$^{th}$ September every year, the contracting authority sends to the contractor an initial written notification informing the latter about the result of the calculation of the yearly price revision. 

The contractor has 30 days following the date of receipt to submit observations against the result of the calculation made by the contracting authority. In absence thereof, the initial written notification sent by the contracting authority acquires the status of an amendment with full legal effect and enters into force the day after the time limit for submitting observations has elapsed. 

Should the contractor formulate any observations on the correctness of the calculation made pursuant to paragraph 1 above within the deadline set out in paragraph 2 above, the contracting authority shall carefully consider them. 

