Tenders describe a solution as the authority envisages it. Suppliers sometimes know a better or cheaper way. Variants are the instrument to bring that way into the procedure without breaking the rules.
The rules
Under Art. 33 PPA and the corresponding IVöB provision, suppliers may submit variants unless the authority excluded or restricted them in the tender, for example to certain parts. The authority may set minimum requirements that variants must also meet. Whether and how variants are permitted is stated in the tender or documents.
The base bid remains mandatory
A variant does not replace the base bid. Submitting only a variant risks exclusion because the bid does not meet the mandatory requirements. The variant is clearly labelled and presented separately from the base bid, with its own price.
When variants pay off
When an alternative solution is significantly cheaper, faster or less risky while achieving the goal equally or better, and when that can be shown against the award criteria. A variant that merely offers your standard solution instead of the requested service rarely convinces. Questions about admissibility belong in the Q&A round.
Distinction from reservations
Reservations or conditions in the base bid are not variants. They change the requested bid and can lead to exclusion. What you want to solve differently belongs in a permitted variant, not in footnotes to the base bid.