(84)Many economic operators, and not least SMEs, find that a major obstacle to their participation in public procurement consists in administrative burdens deriving from the need to produce a substantial number of certificates or other documents related to exclusion and selection criteria. Limiting such requirements, for example through use of a European Single Procurement Document (ESPD) consisting of an updated self-declaration, could result in considerable simplification for the benefit of both contracting authorities and economic operators. The tenderer to which it has been decided to award the contract should, however, be required to provide the relevant evidence and contracting authorities should not conclude contracts with tenderers unable to do so. Contracting authorities should also be entitled to request all or part of the supporting documents at any moment where they consider this to be necessary in view of the proper conduct of the procedure. This might in particular be the case in two-stage procedures – restricted procedures, competitive procedures with negotiation, competitive dialogues and innovation partnerships - in which the contracting authorities make use of the possibility to limit the number of candidates invited to submit a tender. Requiring submission of the supporting documents at the moment of selection of the candidates to be invited could be justified to avoid that contracting authorities invite candidates which later prove unable to submit the supporting documents at the award stage, depriving otherwise qualified candidates from participation. It should be set out explicitly that the ESPD should also provide the relevant information in respect of entities on whose capacities an economic operator relies, so that the verification of the information regarding such entities can be carried out together with and on the same conditions as the verification in respect of the main economic operator.