What is the fundamental difference between additional and supplementary work?

Construction takes shape not only in plans, but also in legal frameworks. In our INspect-LEX Blog, we explain in plain language the legal concepts and rules that define the world of design and construction.
In the first part of our legal blog series, we highlight the essential difference between supplementary work and additional work.

Distinguishing between additional and extra work in design contract performance

One of the greatest difficulties for designers during design projects is determining when requests arising from the client’s expectations or designs prepared based on the contract between the parties can be considered additional or supplementary work.

Section 6:244 of the Hungarian Civil Code generally provides guidance on the distinction between additional and supplementary work.

Additional work:

The contractor shall also perform tasks that are determined in the contract to produce a work but were not taken into account when the contractor’s fee was set, and also those without which the creation of the work suitable for its designated purpose cannot occur.

The designer is therefore obliged to perform any tasks that were not taken into account when determining the fee, or without which the design is not suitable for subsequent implementation or the property cannot be constructed to meet the client’s expectations, without additional remuneration.

Supplementary work:

The contractor shall also perform tasks that were ordered subsequently, in particular those that became necessary due to the amendment of the design, if their performance does not make the work disproportionately more burdensome.

This is clearly a subsequent requirement on the part of the customer, especially if it necessitates changes to the designs. However, this must not place a disproportionate burden on the designer.

In this regard, legislation establishes multiple conditions for the parties involved. Generally, the designer is obliged to carry out subsequently ordered work, or part of it, and is entitled to an additional design fee for doing so. If this would place an unreasonable burden on the designer, they may reject the client’s request for supplementary work.

In the event of a dispute, experts will decide whether additional or supplementary work was required in a given case. However, a properly structured design contract allows the parties to settle this issue in advance as comprehensively as possible.