Contract conditions of December 2015  Contract number: [ complete ]  I.4.2. Price revision index  Price revision is not applicable to this contract.  I.5. PAYMENT ARRANGEMENTS  I.5.1. Pre-financing  Pre-financing is not applicable to this contract.  I.5.2. Interim payment  Interim payment is not applicable to this contract.  I.5.3. Payment of the balance  1. The contractor (or leader in the case of a joint tender) may claim the payment of the  balance in accordance with Article II.20.6. The contractor (or leader in the case of a joint tender) must send an invoice in paper  format for payment of the balance due under the contract, as provided for in the tender  specifications.  2. The contracting authority must approve the submitted documents or deliverables and  pay within 60 days from receipt of the invoice.  3. If the contracting authority has observations to make, it must send them to the  contractor (or leader in the case of a joint tender) and suspend the time limit for payment  in accordance with Article II.20.7. The contractor (or leader in the case of a joint tender) has 20 days to submit additional  information or corrections or a new version of the documents if the contracting authority  requires it. 4. The contracting authority must give its approval and pay within the remainder of the  time-limit indicated in point (2.) unless it rejects partially or fully the submitted  documents or deliverables.  ***   [Option: for contractors for which VAT is due in Belgium:  In Belgium the provisions of  the contract constitute a request for VAT exemption No 450, Article 42, paragraph 3.3 of  the VAT code (circular 2/1978), provided the contractor includes the following statement  in the invoice(s): “Exonération de la TVA, Article 42, paragraphe 3.3 du code de la TVA  (circulaire 2/1978)” or an equivalent statement in the Dutch or German language.]  [In Luxembourg, the contractor must include the following statement in the invoices:  ‘Commande destinée à l’usage officiel de l’Union européenne. Exonération de la TVA  Article 43 § 1 k 2ième tiret de la loi modifiée du 12.02.79.’ In case of intra-Community  purchases, the statement to be included in the invoices is: ‘For the official use of the  [Option: for contractors for which VAT is due in Luxembourg]  7 