Lump Sum Contract: No Payment for Additional Work Without Written Order (Cass. civ. 3e, 25 March 1980)

Imagine: you are having a house built in Seyssinet-Pariset. You sign a contract with a contractor, the price is fixed and final. Work progresses, but the contractor tells you that additional work not planned is necessary. He carries it out, then demands payment. Are you obliged to pay? This question is asked by hundreds of property owners each year. The answer lies in a judgment of the Court of Cassation of 25 March 1980, which is still authoritative today.

In this case, a developer had entrusted the construction of a building complex to a contractor, with a contract providing for a lump sum price (a fixed and final price). Additional work was carried out, but without a written order from the employer (the owner). The contractor then claimed payment for this work in court. The Court of Cassation had to decide: was the contract a lump sum contract? And if so, could the contractor be paid without a written order?

The decision is crystal clear: yes, the contract was a lump sum contract, and no, the contractor cannot claim payment for additional work without a written order signed by the employer. For owners, this is essential protection. For contractors, it is a reminder to be cautious. Let's break down this decision together.

The facts: a story like many that happen every day

In January 1970, a property developer (the employer) entrusted the construction of a building complex to a contractor, Mr Roth. A contract, called a "market", was signed. This contract stated that the price was "fixed and final" and that the work would be settled at the overall price of the tender, increased or decreased by the amount of work carried out in addition or less, but only on a written order after the signing of the contract. In other words, the price is fixed, unless a variation (a signed document) modifies it.

Work began. Over the course of the project, the contractor carried out additional work not provided for in the initial contract. But he did not request a written order from the developer. At the end of the project, the contractor presented his invoice, including this additional work. The developer refused to pay the extra, arguing that the contract was a lump sum contract and that the written order was lacking.

The contractor then sued the developer in court to obtain payment. Did the first instance court rule in his favour? No, the Grenoble Court of Appeal dismissed the contractor's claim. He appealed to the Court of Cassation. He argued that the contract was not a true lump sum contract because the estimate was approximate and the additional work was necessary. The Court of Cassation, in its judgment of 25 March 1980, dismissed the appeal and upheld the Court of Appeal's decision. The contract was indeed a lump sum contract, and without a written order, the contractor could claim nothing.

The reasoning of the court — explained

The Court of Cassation relies on Article 1793 of the Civil Code. This article provides that, in a lump sum contract (a contract where the price is fixed in advance for all the work), the contractor can only demand an increase in price for additional work if it was ordered in writing by the employer, and the price of that work was agreed in advance. In short, no writing, no payment.

But how do you know if the contract is a lump sum contract? The decision gives us clues: the contract mentioned a "fixed and final price" and referred to a particular specification. The fact that the estimate was "approximate" did not change anything: what matters is that the parties referred to a global and final price, with the possibility of modifications only by written order. The Court held that the parties "concluded a contract based on an approximate estimate and by referring to a particular specification stating that the price is fixed and final". It inferred that the contract was a lump sum contract.

The contractor argued that the contract was not a lump sum contract because the estimate was approximate. But the judges did not follow him: the estimate does not contradict the lump sum nature as long as the contract fixes a global price and the parties provided that only written orders could modify it. Another argument of the contractor: the additional work was essential. The Court of Cassation disregarded it: Article 1793 is strict. Even if the work is necessary, without a written order, it remains at the contractor's expense. This is consistent case law: form prevails over substance.

What this means for you — practically

This decision is a protection for employers (owners, developers, co-ownerships). You sign a construction contract at a lump sum price? You know your budget is secure. If the contractor tells you about additional work, you are not obliged to accept: any change must be the subject of a written variation, signed before execution. Otherwise, you can refuse to pay.

Let's take a concrete example. You are a property owner in Saint-Martin-d'Hères and you are having a 30 sqm extension built for a lump sum price of €60,000. During the work, the contractor tells you that the foundations need to be reinforced, for an additional €8,000. He does it without asking you for anything in writing. At the end, he demands an extra €8,000. Thanks to this judgment, you can refuse to pay, because no written order was given.

For contractors, the lesson is clear: never carry out additional work without a written purchase order, signed by the client. Otherwise, you risk not being paid, even if the work was useful or necessary. I had a case where a contractor in Grenoble lost €15,000 for having done additional work without a written order. A simple confirmation email would have sufficed.

For co-owners or syndics: if you sign a works contract for the co-ownership, ensure that any modification is voted on at a general meeting and is the subject of a variation. Otherwise, the syndic could commit the co-ownership without authorisation.

Four tips to avoid this type of dispute

• Insist on a written document for any modification. Before agreeing to additional work, request a detailed quote and sign a variation to the initial contract. A simple email or text message may suffice, but a signed document is better.
• Check the qualification of the contract. Read your contract carefully: if the price is said to be "fixed and final" or "lump sum", you are within the framework of Article 1793. If the contract mentions an "approximate estimate" without further detail, beware: it could be reclassified as a lump sum contract.
• Keep all written documents. Keep quotes, contracts, variations, correspondence, emails. In case of a dispute, these will be your evidence. A client in Seyssinet-Pariset was able to prove the written order thanks to a simple WhatsApp message.
• Do not pay without checking. If the contractor demands sums for additional work without a written order, do not pay. Consult a lawyer first. A 30-minute consultation can save you from paying unduly or, conversely, from being taken to court.

Further information: related case law and developments

This 1980 decision is not isolated. The Court of Cassation has confirmed this position several times. For example, in a judgment of 6 May 1992 (no. 90-17.032), it held that even if the additional work was necessary for the proper execution of the contract, it could not be paid without a written order. Similarly, a judgment of 14 January 1997 (no. 94-22.185) reminded that the lack of a written document prevents any claim for additional price, unless the employer has expressly accepted the work subsequently. But beware: this acceptance must be unequivocal, for example by paying part of the work without reservation.

The trend is therefore towards strictness: the courts protect the employer against budget overruns. For professionals, it is imperative to formalise any modification in writing. The judges are deaf to arguments of necessity or urgency: without a written document, no payment. This case law is still current, and recent decisions confirm it.

Summary and next steps

Here is a checklist of actions to take if you are faced with a demand for additional work without a written order:

1. Do not pay until you have verified the existence of a written order.
2. Ask the contractor to provide you with written proof of your order (email, letter, signed variation).
3. Consult a lawyer if the contractor insists or threatens legal action. A lawyer specialising in property law can assess your situation.
4. If you are the contractor, regularise the situation: have a variation signed immediately, even after the work if the client agrees.
5. In the future, include a clause in your contracts stating that any modification must be the subject of a written document signed by both parties.

In summary, this 1980 judgment is a safety net for owners and a warning for contractors. The rule is simple: no writing, no payment. If you are in doubt, seek advice promptly.

Are you in a similar situation? A first 30-minute consultation with Maître Zakine (€45) can save you months of proceedings — and often much more. Book an appointment →