A modification clause (change control or variations clause) regulates in advance how parties agree on, price, and legally anchor adjustments. No contract is static. Scope, price, delivery dates, or technology may change. In our practice, we see that entrepreneurs often handle changes informally — a mistake that proves costly in the event of a dispute. A formal procedure protects both parties.
What is the legal problem?
A change in scope requires an adjustment in price, planning, or the party bearing the risk. Without a procedure, uncertainty arises regarding when a change has been accepted and what consequences it has. Internationally, rules regarding oral changes and conduct vary. Under common law, a no-oral-modification rule often applies; under civil law, conduct carries more weight.
What does the law say?
Under Dutch law, freedom of form applies; Amendments may be made orally or implicitly under Section 6:217 of the Dutch Civil Code. Under English law, case law strongly recognizes no-oral-modification clauses (Rock Advertising v MWB Business Exchange, 2018). The Vienna Sales Convention stipulates in Article 29 CISG that amendments may also be implicit, but that a written requirement is in principle respected.
FIDIC models feature detailed variation order procedures under Clause 13 (FIDIC 2017). For consumers, mandatory rules apply that limit unilateral amendment under Section 6:236 sub i of the Dutch Civil Code.
What risks do companies face?
An awkward amendment process leads to the loss of additional compensation for extra work. Insufficient formality regarding amendment makes it contestable. In large contracts, dozens of variation orders without structure can lead to scope creep and uncontrollable cost overruns. Among international parties, ambiguity arises due to differing expectations regarding formal confirmation.
Practical example from our practice
We advised a Dutch IT supplier who implemented changes at the request of a Belgian client without a formal change order. Upon invoicing, the client refused payment for €420,000 in additional work because the changes had not been ordered. The Belgian court ruled in favor of the client due to insufficient evidence. Upon renegotiation, we incorporated the following: written change request, impact assessment within 5 working days, quotation within 10 working days, signed change order required for execution, and a no-oral-modification clause.
What can you do?
Arrange a formal process: written change request, impact assessment, quotation, and signed change order. Agree on who is authorized to act on behalf of each party. Build in deadlines for decision-making. Combine with a no-oral-modification clause. For projects with many changes: change control board. Document everything. See also our article on international construction contracts.