Public contracts can be modified after signature, but EU law draws a hard line between permissible adjustments and changes so substantial they amount to a new contract that should have been tendered.
When modification is allowed (Article 72)
The Directive lists specific safe harbours:
Review clauses: If the original contract included clear, precise, and unequivocal review clauses (price indexation, option extensions, scope adjustments), those can be activated without a new procedure. The clauses must have been visible to all bidders during the original competition.
Additional works/services: Up to 50% of the original contract value for works, services, or supplies not included in the initial procurement, provided they are necessary and changing contractor is not feasible for economic or technical reasons.
Unforeseeable circumstances: Changes necessitated by circumstances a diligent authority could not have foreseen. The overall nature of the contract must not be altered, and the increase cannot exceed 50% of the original value.
De minimis changes: Modifications below both the EU threshold and 10% of the original value (15% for works) that do not alter the overall nature.
Supplier substitution: Only when the original contract includes a review clause for this, or through corporate succession (merger, insolvency, restructuring) where the new entity meets the original selection criteria.
When modification is NOT allowed
A modification requires a new procurement if it:
- Changes the economic balance in favour of the contractor in a way not provided for in the original terms
- Extends the scope considerably beyond the original contract
- Would have attracted different bidders or led to a different winner had it been part of the original procedure
The Pressetext test
Before Article 72 codified these rules, the CJEU established in Pressetext (C-454/06, 2008) that a modification is "material" — and therefore requires re-tendering — if it introduces conditions which, had they been part of the original procedure, would have allowed different tenderers or a different outcome. Article 72 essentially codifies this case law.