Amendments to procurement documents will be provided simultaneously to all operators by the same means as for the procurement documents. 

In order to allow economic operators reasonable time in which to take the amendment into account in preparing their requests to participate/tenders, Europol, at its discretion, may extend the time limit for receipt of requests to participate/tenders. 

Amendments will be regarded as an integral part of the procurement documents. 

## 4.3. Contacts with candidates/ tenderers following submission of requests to participate/tenders 

Except in duly justified cases, candidates/ tenderers who have failed to submit evidence or to make statements as required in the procurement documents, shall be contacted by the contracting authority to provide the missing information or clarify supporting documents. 

The contracting authority may correct obvious clerical errors in the tender after confirmation of the correction by the tenderer. Such information, clarification or confirmation shall not substantially change the tender. 

Only in the case of a negotiated procedure, if so stated in the Invitation, Europol may negotiate with tenderers the tenders they have submitted, in order to adapt them to the requirements set out in the procurement documents and in order to find the most economically advantageous tender. The minimum requirements defined in the procurement documents are not subject to negotiation. During negotiations equal treatment of all tenderers will be ensured. Europol reserves the right not to negotiate and to award the contract on the basis of the tenders initially received. 

## 5. Submission of requests to participate/tenders, opening and evaluation 

## 5.1. Submission of requests to participate/tenders 

The candidates/ tenderers must observe the time limit for receipt of requests to participate/ tenders as specified in the Invitation. 

Depending on the type and value of the procurement procedure, requests to participate/tenders shall be submitted either electronically or as hard-copy via post/courier/hand delivery. 

Detailed information about the specific modalities of submission for each procedure is provided in the Invitation. 

## 5.2. Opening session 

Requests to participate/tenders submitted in accordance with the specified rules shall be opened by Europol in an opening session. 

In open procurement procedures, the opening session is public, with the meaning that any authorised representative of the tenderer may attend the opening session. The Invitation or Contract Notice will specify whether the opening session is public. 

