What changes in 2027 with Book 7 of the Civil Code

The law has been passed and published, but Book 7 is not yet in force. The Act of 22 July 2026 inserts into the Civil Code a Book 7, "Les contrats spéciaux" (special contracts). It was published in the Moniteur belge (Belgian Official Gazette) on 23 September 2026. Its article 50 sets entry into force on the first day of the twelfth month following the month of its publication (only its articles 6, 8, 11, 14 and 15 enter into force on the tenth day after publication), and Justel states for Book 7: "Entry into force: 1 September 2027" (unofficial translation, as are all quotations of Belgian texts in this article).

The transitional rule in article 49 of the Law works in two stages. Book 7 applies to legal acts and facts occurring after its entry into force. Unless the parties agree otherwise, the previous rules remain applicable to the future effects of earlier acts, as well as to later acts that relate to an obligation arising from an earlier act.

An amendment or convention additionnelle (additional agreement) signed after 1 September 2027 to a contract concluded before that date in principle remains under the old regime. Article 49, second paragraph, 2°, keeps the previous rules, unless otherwise agreed, for later legal acts that relate to an obligation arising from an earlier act. An amendment that adds new works, rather than adjusting the existing obligations, deserves case-by-case examination, and a client signing it states in writing which regime the parties intend to apply.

The lump sum protects, on one written condition. Article 1793 of the old Civil Code provides that the architect or contractor who has undertaken the lump-sum construction of a building, according to a plan settled and agreed with the owner of the land, "may not claim any increase in price", neither on the ground of increased labour or materials costs nor on the ground of changes or additions to the plan, "if those changes or additions have not been authorised in writing, and the price agreed with the owner". Its effects on the budget are covered in the article on extras in a private lump-sum contract.

Termination has a price. Article 1794 allows the client to terminate the lump-sum contract by its own will alone, compensating the contractor for its expenses, its work and everything it could have earned.

Hardship already exists. Article 5.74 of the Civil Code (Book 5) applies to contracts concluded since 1 January 2023; it is a default rule, which the contract can set aside.

Ten-year liability of the architect and the contractor is found in article 1792. Book 7 carries it over, in a restructured form, in article 7.4.57.

Default rules, in principle. Article 7.1.1 provides that the provisions of Book 7 are default rules, except where they are mandatory. The contract therefore keeps control over the points that affect the budget, except for mandatory provisions such as ten-year liability.

The lump-sum principle is maintained. The service provider performs for the agreed price; under a lump sum, it "may not claim any increase, even if the service required more work or expense than had been anticipated".

A door opens: renegotiation. The service provider may request renegotiation if five cumulative conditions are met: pre-existing circumstances make performance excessively onerous; they could not have been known; they are not attributable to the provider; the provider did not assume that risk; and that possibility has not been excluded. Failing agreement, the court may adapt the contract or bring it to an end. The article reserves the application of article 5.74 on hardship.

Effect on the budget. For a lump sum concluded under Book 7, the risk of unforeseen conditions (ground, poorly known existing building) may no longer be entirely absorbed by the price: when the five conditions are met, the contractor may request renegotiation and then go to court. The client therefore decides, at drafting stage, whether to exclude that possibility, to make the contractor assume the risk by an express clause, or to keep it and make provision for it. Preliminary investigations (trial pits, surveys of the existing building) also reduce the share of circumstances that "could not have been known".

The right to terminate remains, and so does the compensation. The client may terminate the fixed-term contract at any time; if it was concluded for payment, the client compensates expenses, losses, services performed and, unless custom provides otherwise, loss of profit. For the budget, the logic remains that of article 1794: an exit that is possible, and that must be provided for.

A section specific to construction. Article 7.4.55 covers contracts for the construction, alteration or demolition of an immovable work, and related intellectual services: the contract of the architect, the quantity surveyor or the project manager concluded after 1 September 2027 will therefore also be governed by Book 7.

Acceptance is given a definition. Article 7.4.56 links provisional acceptance to "retirement" (taking delivery) and final acceptance to "agréation" (approval).

Ten-year liability is maintained. Article 7.4.57 provides for a 10-year liability for defects that threaten the stability or soundness of the work, and makes any clause that excludes or limits it absolutely void.

The finding. In its section on immovable works, Book 7 does not carry over the written authorisation rule of article 1793. In the articles read (7.4.1 to 7.4.33 and 7.4.55 to 7.4.57), no provision reproduces the requirement of a change authorised in writing and a price agreed with the owner. The explanatory statement of the bill confirms this: the rule is abolished because it departs from the general law of contract, the client's protection resting instead on the contractor's duty to warn of the financial implications of the changes envisaged.

This finding does not mean that no written document will be needed any more. The contract remains binding between the parties, and the proof of a change and of its price still lies with the party relying on it.

It has a practical consequence. Today, article 1793 gives the client statutory protection, without any particular clause, within its scope (lump sum, building, plan settled and agreed). For contracts concluded from 1 September 2027, the client has every interest in providing in the contract for a written change procedure: written instruction, prior quotation, price agreed before execution, signature of the authorised person, and the fate of works carried out without that agreement. On the architect's side, the priced additional agreement required by the code of ethics of the Order of Architects of 16 November 2022 (art. 16) derives from a text other than the Civil Code.

Five precautions apply from today, whatever the regime of the contract. They are taken when the contract is drafted, not when a dispute arises:

• Date each contract unambiguously. The date of conclusion decides the regime; for a contract negotiated during the summer of 2027, it must be certain and in writing.
• Write the change procedure into every contract. Useful today, in addition to article 1793, it becomes the main tool for controlling extras in contracts concluded from 1 September 2027.
• Take a position on unforeseen conditions: exclude renegotiation, allocate the risk or make provision for it. The choice is made at drafting stage, not when the ground springs a surprise.
• Make provision for termination in projects where an early exit is conceivable, under either regime.
• Update contract templates before September 2027, with reference to the articles of Book 7.

The division between the architect's contract and the works contract is presented in the article on architect and works contracts, and other developments in construction law in the article on developments to monitor. The general framework, who manages cost and who signs what, is set out in the branch article on who manages cost for the client.