(1) Significant modifications to a public contract during its term require a new procurement procedure. Modifications are significant if they result in the public contract differing substantially from the public contract originally awarded. A significant modification exists in particular where
1. the modification introduces conditions which, if they had applied to the original procurement procedure,
a) would have made it possible to admit other candidates or tenderers;
b) would have made it possible to accept a different tender; or
c) would have drawn the interest of further participants in the procurement procedure;
2. the modification shifts the economic balance of the public contract in favour of the contractor in a manner that was not provided for in the initial contract;
3. the modification significantly extends the scope of the public contract; or
4. a new contractor replaces the contractor in cases other than those provided for in subsection (2) no 4.
(2) Notwithstanding subsection (1), it is permissible to modify a public contract without conducting a new procurement procedure where
1. the initial procurement documents provide clear, precise and unequivocal review clauses or options which contain statements on the scope and nature of and requirements for possible contract modifications, and the overall nature of the contract is not altered by the modification;
2. additional supplies, works or services become necessary which were not provided for in the initial procurement documents and a change in the contractor
a) cannot be made for economic or technical reasons and
b) would cause significant inconvenience or substantial duplication of costs for the public contracting authority;
3. the need for modification has been brought about by circumstances that a diligent public contracting authority could not have foreseen, and the overall nature of the contract is not altered by the modification; or
4. a new contractor replaces the previous contractor
a) based on a review clause within the meaning of no 1;
b) based on the fact that a different undertaking that meets the requirements originally set for eligibility replaces the original contractor, wholly or in part, following corporate restructuring through, for example, takeover, merger, acquisition or insolvency, provided that this does not entail further material modifications within the meaning of subsection (1); or
c) based on the fact that the public contracting authority itself assumes the main contractor's obligations towards its subcontractors.
In the cases referred to in sentence 1 nos 2 and 3, the price may not be increased by more than 50 per cent of the value of the original contract. Where there are several successive modifications of the contract, this limitation applies to the value of each individual modification, provided that the modifications were not made with the aim to circumvent the provisions of this Part.
(3) It is also permissible to modify a public contract without conducting a new procurement procedure if the overall nature of the contract is not altered and the value of the modification
1. does not exceed the respective thresholds under Section 106 and
2. does not amount to more than 10 per cent of the original contract value in the case of contracts for supplies and services and not more than 15 per cent in the case of works contracts.
Where there are several successive modifications, the total value of the modifications is applicable.
(4) Where the contract includes an indexation clause, the higher price shall be the reference value for calculating the value under subsection (2) sentences 2 and 3 and subsection (3).
(5) Modifications under subsection (2) nos 2 and 3 shall be published in the Official Journal of the European Union.