Lump Sum Works Contract: The Architect May Wait for All Invoices Before Checking Yours

You have just had an extension built on your house in Limoges. The quotation stated a lump sum price: €85,000, all inclusive. The works are finished, but the architect refuses to check your invoice (the detailed bill) until all other trades have submitted theirs. Result: you have been waiting for three months, and the contractor is demanding an additional €8,000 for 'unforeseen items'. Unfair term or lawful practice?

The Court of Cassation answered this question in 1995 in its decision No. 93-15.332. A SCI (property investment company) had ordered works based on an estimated quotation, with a price presented as lump sum. But the contract stipulated that the architect would only check each invoice after receiving all invoices. The SCI, believing it had paid too much compared to the work actually carried out, sought to have the clause annulled, arguing that it was incompatible with the lump sum. The Court decided otherwise.

What exactly does this decision say? What are its consequences for an owner in Guéret or a developer in Limoges? And how can you avoid finding yourself in a deadlock? We analyse this decision together, its practical implications, and the reflexes to adopt.

The Facts: A Story Like Many Others

In the early 1990s, a SCI entrusted a company with construction works, based on estimated and quantitative quotations. The contract stated that the price was 'net and lump sum', and a clause stipulated that 'the company accepts that its invoice will only be checked by the architect when the latter is in possession of all invoices'. In other words, the architect waits to receive the invoices of all contractors (plumber, electrician, etc.) before examining that of the company.

The works progress. The SCI pays instalments. But at the time of completion (the formal acknowledgement that the works are finished), the SCI realises that the total amount paid exceeds the value of the works actually carried out compared to those in the contract. It believes it has overpaid. The SCI then sues the company, demanding restitution of the sums unduly paid. Its main argument: the clause on deferred verification of invoices is inconsistent with the concept of a lump sum. For it, a lump sum implies a fixed and final price, which cannot be conditioned on a later global verification.

The Limoges Court of Appeal? No, the case was heard by the Poitiers Court of Appeal, then the Court of Cassation. The SCI lost on appeal and then appealed to the Court of Cassation. It argued that the disputed clause distorted the lump sum, as it allowed the architect to modify the price afterwards by playing with the quantities. The Court of Cassation dismissed the appeal. On 17 May 1995, it confirmed that the clause was not incompatible with the lump sum nature of the contract.

The Reasoning of the Court — Analysed

The Court of Cassation had to decide a legal question: is a clause that subordinates the verification of a company's invoice to the receipt of all other invoices compatible with a lump sum contract? To understand this, we must first recall what a lump sum contract is. The Civil Code, in its former article 1793 (now article 1793 of the Civil Code), provides that the employer (the owner) who entrusts works to a contractor at a lump sum price cannot demand a reduction in the price on the ground that the works cost less, nor can the contractor demand an increase on the ground that they cost more. The lump sum is a fixed and final price, except in cases of modifications accepted by both parties.

The SCI argued that the deferred verification clause opened the door to price adjustments, as the architect could, by delaying verification, contest quantities or prices. But the Court of Cassation held that the mere provision of an order of verification does not undermine the lump sum nature of the price. Why? Because the lump sum covers all the services, not the detail of each invoice. The architect checks that the declared quantities correspond to the works carried out, but the overall price remains that initially fixed, unless there is a variation order (a written agreement modifying the contract).

The Court noted that the contracts were established on the basis of estimated and quantitative quotations requested by the SCI, and that the tender (the company's offer) stated that the price was net and lump sum. Therefore, the verification clause was merely a practical control mechanism, without impact on the price. The judges therefore upheld the appeal decision. This is a dismissal decision, confirming previous case law: the lump sum does not require immediate and individualised verification of invoices.

What This Changes for You — Concretely

For an owner having a house built or renovated in Limoges, this decision means that you cannot object to a clause requiring global verification of invoices by invoking the lump sum. If your contract provides that the architect waits for all invoices to examine them, this clause is valid. But be careful: this does not mean that the architect can indefinitely delay verification. The contract must set a reasonable time limit. Failing that, you could invoke an abuse of right (article 1240 of the Civil Code, which penalises abuse in the exercise of a right).

For a contractor, this is a safeguard: you can accept this type of clause without fearing that it invalidates the lump sum. But be vigilant: if the architect delays too long, you can serve a formal notice (by registered letter with acknowledgement of receipt) to verify your invoice within a certain period, for example 30 days. After this period, you could claim late payment interest or damages.

Let's take a concrete example in Guéret. A couple has a house built for a lump sum of €250,000. The architect waits for the invoices of six companies. The masonry company, which has finished its work, must wait three months for its invoice to be verified. Meanwhile, it cannot invoice the balance of €30,000. If the contract does not provide for a time limit, the couple may face tensions with the company, or even a formal notice. The solution: provide in the contract a maximum verification period, for example 60 days after receipt of the last invoice.

If you are in this situation, you should check your contract. Look for the clause on verification of invoices. If it is vague, request a variation order specifying a schedule. And if a dispute arises, do not wait: a quick consultation with a specialist lawyer can save you months of proceedings.

Four Tips to Avoid This Type of Dispute

• Require a verification schedule: in your project management contract (the contract with the architect), have a maximum period specified between the submission of the last invoice and the verification of all invoices. For example: 'The architect shall verify the invoices within 30 days of receipt of the last invoice.'
• Provide for late payment penalties: if the architect exceeds the deadline, penalties of 1% of the invoice amount per week of delay may be stipulated. This encourages diligence.
• Use a single invoice date: for small projects, ask each company to submit its invoice by a common deadline. Thus, the architect receives all invoices at the same time and can verify them quickly.
• Have the invoice approved by the architect progressively: negotiate a clause allowing partial verification. For example, the architect verifies each invoice individually within 15 days of its submission, and the balance is paid immediately. The global clause only applies in case of dispute.

Further Details: Related Case Law and Developments

This 1995 decision is part of a series of decisions that protect contractual freedom in works contracts. The Court of Cassation has, for example, held in 1992 (Civ. 3e, 10 June 1992, No. 90-18.522) that a clause in a lump sum contract providing for the price to be revised according to the construction cost index was not incompatible with the lump sum, provided the revision was limited and provided for in the contract. Conversely, in 2001 (Civ. 3e, 13 June 2001, No. 99-17.234), the Court overturned a decision that had upheld a clause allowing the architect to unilaterally modify the price after signature, considering it an infringement of the lump sum.

The trend is therefore as follows: the lump sum is a rigid framework, but the practical arrangements for monitoring and verification can be contractually organised, as long as they do not undermine the overall price. Since 1995, courts have become increasingly vigilant about clauses that create a significant imbalance between the parties, particularly since the introduction of the concept of unfair terms in the Consumer Code (Article L. 212-1). If the global verification clause is imposed by a professional on a consumer (non-professional owner), it could be challenged if it creates an excessive delay. But in business-to-business relationships, contractual freedom remains the rule.

Checklist Before Taking Action

FAQ: Your Frequently Asked Questions

1. Can I refuse to sign a contract with a global verification clause for invoices?
   Yes, you are free to negotiate. If the architect refuses to modify the clause, you can turn to another professional. In practice, this clause is common, but you can ask to add a maximum time limit.
2. What should I do if the architect delays verifying my invoice?
   Send a formal notice by registered letter with acknowledgement of receipt, setting a 15-day deadline. After this period, you can apply to the judicial court to obtain payment of the sums due, with interest.
3. Can an unverified invoice be considered accepted?
   No, in principle. But if the architect keeps the invoice without reacting for an abnormally long time (several months), a judge might consider that there has been tacit acceptance. It is therefore important to prove your reminders.
4. Does this clause also apply to renovation works?
   Yes, regardless of the type of works, as long as the contract provides for a lump sum and verification by a project manager (architect, design office).
5. What remedies do I have if the architect refuses to verify the invoice without justification?
   You can invoke poor performance of his project management contract and claim damages for the harm suffered (late payment to the company, penalties you have to pay). Consult a lawyer specialising in property law.

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 →