Within three years following the signature of the contract(s) resulting from the current call for  tenders, the  Contracting authority may use the negotiated procedure under point 11.1.e of  Annex 1 to Regulation (EU, Euratom) 2018/1046 of the European Parliament and of the  Council of 18 July 2018 on the financial rules applicable to the general budget of the Union 1 to procure new services from the contractor(s) up to a maximum of 50 % of the initial  contract value. These services will consist of the repetition of similar services entrusted to the  contractor(s). The conditions for award will be specified in the tender specifications of the  negotiated procedure.  The tasks should be completed within  15  months of the signature of the contract. The execution  of the tasks may not start before the contract has been signed.  For all exchanges with the contractor during the implementation of the contract as well as for  future possible subsequent proceedings for the purposes of EDES (European Union's Early  Detection and Exclusion System) the  Contracting authority  may use an electronic exchange  system meeting the requirements of Article 148 of Regulation (EU, Euratom) 2018/1046 of the  European Parliament and of the Council of 18 July 2018 on the financial rules applicable to the  general budget of the Union $^{1}$. At the request of the  Contracting authority  the use of such a  system shall become mandatory for the contractor(s) at no additional cost for the  Contracting  authority . Details on specifications, access, terms and conditions of use will be provided in  advance.  1.9. Electronic exchange system: can exchanges under the contract be automated?  1.8. Duration of the contract  12