 2019  Contract number: [ complete ]  If no observations have been submitted or if, despite the observations submitted, the contracting  authority decides to pursue the recovery procedure, it must confirm recovery by  formally  notifying  a debit note to the contractor, specifying the date of payment. The contractor must pay  in accordance with the provisions specified in the debit note.  If the contractor does not pay by the due date, the contracting authority may, after informing  the contractor in writing, recover the amounts due:  If the contractor does not honour the obligation to pay the amount due by the date set by the  contracting authority in the debit note, the amount due bears interest at the rate indicated in  Article II.21.8. Interest on late payments will cover the period starting on the day after the due  date for payment and ending on the date when the contracting authority receives the full amount  owed. Any partial payment is first entered against charges and interest on late payment and then  against the principal amount.  If the contract is signed by a group (joint tender), the group is jointly and severally liable under  the conditions set out in Article II.6 (liability). The contracting authority first claims the full  amount to the leader of the group. If the leader does not pay by the due date and if the amount cannot be offset in accordance with  Article II.23.2 (a), the contracting authority may claim the full amount to any other member of  the group by  notifying  the debit note already sent to the leader under Article II.23.2. Such checks and audits may be initiated at any moment during the  provision of services and up to five years, starting from the payment of the balance of the last specific  contract issued under this FWC. The audit procedure is initiated on the date of receipt of the relevant letter sent by the  contracting authority. Audits are carried out on a confidential basis.  II.24.1 The contracting authority and the European Anti-Fraud Office may check or require  an audit on the  implementation of the FWC . This may be carried out either by OLAF’s  own staff or by any other outside body authorised to do so on its behalf. (a) by offsetting them against any amounts owed to the contractor by the European Centre  for Disease Prevention and; (b) by calling in a financial guarantee if the contractor has submitted one to the  contracting authority; (c) by taking legal action. II.23.2  Interest on late payment  II.23.3  Recovery rules in the case of joint tender  II.24. CHECKS AND AUDITS  38 