The conclusion of a contract for work or a fee contract is subject to public procurement law. It is therefore imperative that the following award principles are observed in the selection process.
Please note the following points:

Transparency

A detailed description of services has been drawn up. The individual steps (in particular the passing on of information and the course of negotiations) must be recorded in documentation.

Economic efficiency

At least 3 written, individualized offers.
The most economical offer is awarded the contract.

Proportionality

Definition of the suitability criteria in relation to the specifications.

Equal treatment/competition

Correct choice of award procedure (priority open procedure with the possibility of opening a competition with equal access for candidates), obligation to change suppliers, product neutrality.

Special case of unique selling proposition

If there is a unique selling proposition, this must be defined exhaustively.