Public buyers cannot simply pick a supplier. They must run one of a small set of defined procedures, and the tender will tell you which one applies. Knowing the procedure tells you how the competition will run and how much room there is to negotiate.
Short answer: Under EU rules there are a few main procedures. The open and restricted procedures are the standard routes. The competitive procedure with negotiation, competitive dialogue and innovation partnership are used for more complex needs. A negotiated procedure without prior publication exists for exceptional cases. They are set out in Directive 2014/24/EU.
Open procedure
Any interested supplier can submit a full offer in response to the published tender. There is no separate shortlisting step. The open procedure is the most common and the most straightforward, and it suits clearly defined needs.
Restricted procedure
This runs in two stages. First any supplier can ask to take part, and the buyer shortlists those that meet the selection criteria. Only the shortlisted suppliers are then invited to submit a full offer. It suits markets with many potential bidders, where evaluating every full offer would be impractical.
Competitive procedure with negotiation
The buyer publishes its needs, receives initial offers, and then negotiates with suppliers to improve them before final offers. It is used when an off-the-shelf solution will not do and the buyer needs to shape the offer through discussion.
Competitive dialogue
For complex contracts where the buyer cannot define the solution in advance, it opens a dialogue with shortlisted suppliers to develop one or more workable solutions, then asks for final tenders against the chosen approach.
Innovation partnership
Where the market does not yet offer what the buyer needs, this procedure lets the buyer partner with suppliers to develop a new solution and then buy the result, all within one structured process.
Negotiated procedure without prior publication
This is the exception, not the rule. It allows a buyer to award a contract without a published competition, but only in narrow, justified circumstances. For most suppliers, the open and restricted procedures are what you will meet.
FAQ
Which procedure is most common? The open procedure, where any supplier can submit a full offer directly.
When can a buyer negotiate? In the competitive procedure with negotiation and in competitive dialogue, both reserved for more complex needs.
Where are these procedures defined? In Directive 2014/24/EU, which each EU country implements in its own national law.