Non-Substantial Modification

Not every change to a public contract triggers the need for a new competition. The European procurement framework recognises that contracts are living instruments that must respond to changed circumstances, and it provides a set of safe harbours for changes that do not distort competition. These are non-substantial modifications: amendments that fall below the legal threshold for requiring a fresh procurement procedure.

What is a non-substantial modification?

A non-substantial modification is one that does not meet the substantiality tests in Article 72(4) of Directive 2014/24/EU. Practically speaking, a modification is non-substantial where it would not have attracted different tenderers or allowed a different winner in the original competition; where it does not change the economic balance of the contract in the contractor's favour; where it does not considerably extend the scope; and where no unauthorised change of contractor occurs.

Non-substantial modifications are lawful without a new procedure when they also satisfy one of the five permitted grounds in Article 72(1) and (2): they were anticipated in a review clause; they concern additional works, services or supplies within the permitted threshold; they result from unforeseen circumstances; they involve a permitted contractor substitution; or they qualify as a de minimis modification below the relevant value threshold.

A price revision clause agreed at contract signature, for instance, allows the contract price to be adjusted according to a published index without any of those adjustments constituting a new award. Such adjustments are non-substantial by design, because the mechanism was part of the original competitive offer.

In the UK, the Procurement Act 2023 preserves the same core logic. A change that would not have affected the outcome of the original competition, and falls within one of the permitted grounds, can be made without reopening the market.

Why it matters for bidders

Understanding which modifications are non-substantial matters in two contexts. As a bidder, you should assess the modification provisions in any contract you are about to sign. A contract with well-drafted review clauses and price revision mechanisms will give both you and your client flexibility to respond to change without legal risk. As a market observer, you can use modification notice publications to track how authorities are changing contracts with competitors, and assess whether those changes look lawful.

It is also worth noting that the cumulative effect of a series of individually non-substantial modifications can, over time, render the overall change substantial. Contracting authorities should keep a record of all modifications made and their aggregate value to avoid inadvertently crossing the substantiality line through incremental change.

Example

A Belgian federal agency holds a three-year document management contract with a price revision clause linked to Belgium's health index. Each year, the contract price is adjusted upward by 2.1%, 1.8%, and 2.3% respectively, in line with the index. Each adjustment is a non-substantial modification: it was anticipated in the original documents, does not change the competitive balance, and simply executes a pre-agreed mechanism.

Frequently Asked Questions

Can multiple small modifications together become substantial?

Yes. Article 72(4) makes clear that a series of successive modifications designed to circumvent the procurement rules is impermissible. Authorities must look at the cumulative effect of modifications, not just each one in isolation. If the aggregate change would be substantial, the modification strategy is unlawful.

Does a non-substantial modification need to be documented?

Yes, thorough documentation is essential even for non-substantial modifications. The contracting authority must be able to demonstrate, if challenged, that the modification was non-substantial and fell within a permitted ground. A signed variation order or supplementary agreement is the standard vehicle.

Do non-substantial modifications need to be published?

Only some. Modifications made under Article 72(1)(b) or (c) that exceed certain value thresholds must be published in OJEU via TED. Purely administrative or minor value adjustments typically do not. In the UK, the Procurement Act 2023 introduced a broader modification notice publication obligation for significant modifications.