1. What the code is and when it applies
The code applies to contracts placed by public buyers: the State, local authorities, public bodies, and private-law organisations charged with a public service mission. For the economist the first question is always: who is the client? If it is a buyer within the meaning of the code, all of its rules apply, including those on price, on changes during performance, and on completion.
The code does not apply to private contracts, even where the funding includes public subsidy. A scheme half-funded by a region for a private developer remains a private contract. Only if the client itself is a public buyer does the code bite.
ℹ Three cumulative tests First, the buyer: is it a public-law legal person, the State, a local authority, a public body, or a private-law organisation charged with a public service mission? If so, the code applies. Second, the subject matter: is it a contract for consideration concluded to meet the buyer's needs, whether works, supplies or services? If so, the code applies. Third, the threshold: below the exemption threshold, 100 000 € excluding VAT for works since 1 January 2026 (exemption from advertising and competition, R2122-8, for consultations launched since that date), the rules are lighter and the contract can be placed without advertising or formal competition. Above the European threshold, 5 404 000 € excluding VAT for works since 1 January 2026 (European threshold, notice on procedural thresholds, annex no. 2 to the code, JORF of 13 January 2026), the formal procedures apply.
2. How the code is structured
| Part | Main articles | Key economic content | What it means for the economist |
|---|---|---|---|
| Part 1, general provisions | L. 1 to L. 99 | Definitions, scope, the fundamental principles of open access, equal treatment and transparency | It frames the whole logic of public contracting; compliance with the principles determines validity |
| Part 2, public contracts | L. 2100 to L. 2399 | Placing, procedures, thresholds, performance, price, changes, termination | The heart of the law; the articles on price and on changes are fundamental |
| Part 3, concessions | L. 3100 to L. 3399 | The concession regime, distinct from a public contract | Marginal for the economist except on partnership schemes |
| Part 4, private-law bodies subject to the code | L. 4100 to L. 4200 | Local public companies and certain subsidised bodies | To be identified at the start of the commission; it determines which rules apply |
| The regulatory part | R. 2100 to R. 2399 | Thresholds, procedures, standard conditions, the content of the contract documents, warranties, price and adjustment | Articles R. 2112, R. 2152, R. 2194 and R. 2391 are the economist's daily references |
The regulatory part is what the economist consults day to day. The L. articles set the principles; the R. articles turn them into precise operational obligations: the content of the contract documents, the forms of price, the procedure for analysing tenders, the conditions for change, the payment periods.
3. The eight articles that govern a works contract
| Article | Subject | What it changes in practice | Classic error if ignored |
|---|---|---|---|
| R. 2112-1 to R. 2112-16 | Types and forms of price: fixed, updatable, adjustable | A fixed price is the rule; an adjustable price is the exception and requires an explicit formula in the conditions of contract | Applying an adjustment that the contract never provided for, which is unenforceable |
| R. 2152-1 to R. 2152-11 | Selection criteria and weighting | The criteria and their weighting are set in the tender instructions; the abnormally low tender is an analysis, not a separable criterion | Confusing the analysis criteria with the published selection criteria, which unsuccessful tenderers can challenge |
| R. 2152-3 | Abnormally low tenders | The buyer must ask for justification on any tender that may be abnormally low, and may reject it where the justification is inadequate | Failing to trigger the procedure on a low tender, which carries a legal risk for the buyer and a failure risk on site |
| L. 2194-1 to L. 2194-6 and R. 2194-1 | Changes during performance | A contract can be changed without a new procedure in the six exhaustive cases of article L2194-1, including circumstances a diligent buyer could not foresee (R2194-5) | A variation exceeding the statutory ceilings with no fresh competition, which risks annulment |
| R. 2191-1 to R. 2191-60 | Financial performance, price, payment, interest | The public payment period is 30 days, with interest running automatically beyond it | Forgetting the interest in the final account, which the contractor later claims |
| R. 2391-1 to R. 2391-25 | Certificate of works done and completion | Completion starts the warranty periods running, and snags have to be cleared within the contract period | Accepting defective work without snags, which loses the right to withhold at final account |
| L2113-10 and L2113-11, R2113-1 to R2113-3 | Splitting the works into packages | The works must be split unless the buyer justifies otherwise in writing; each package is a separate contract | Not splitting without justification, which makes the procedure unlawful |
| R. 2112-13 to R. 2112-16 | The price adjustment formula | The parametric formula must use published indices, and is compulsory where the parties are exposed to major hazards during performance (R2112-13) and, with a reference to official indices, for a contract of more than three months that requires a large share of supplies whose price directly follows world market prices (R2112-14) | A formula built on unpublished indices, which is unenforceable |
The two to keep uppermost, the abnormally low tender article and the changes articles, are the most frequent sources of litigation on public works. The first because buyers omit to trigger the procedure on low tenders for fear of antagonising contractors, which exposes them to liability if the contractor then fails. The second because variations beyond the statutory ceilings without fresh competition expose the buyer to annulment and the design team to a claim.
4. The price regime
This is where the code imposes the most that is specific against private practice. The rules on the forms of price and on adjustment sit in articles R. 2112-1 to R. 2112-16.
The fixed price
A fixed price does not move during the contract. For works, a fixed-price contract must provide for the arrangements for updating its price (R2112-10). The price is updated if more than three months pass between the date on which the tenderer set its price in the tender and the date on which performance begins, to the economic conditions of a date three months before performance begins (R2112-11); the price so updated remains fixed throughout the period of performance and is the settlement price (R2112-9). If the contract refers to the CCAG-Travaux 2021, the date the price is set is that of the tender, or of the final tender after negotiation, and, where the contract defines no index, the coefficient is set by variation from the INSEE BT or TP index corresponding to the works (art. 9.4.2 and 9.4.3).
The adjustable price
An adjustable price moves during the contract according to a parametric formula set in the conditions of contract. It is compulsory on works contracts running more than three months that require a large share of supplies, in particular raw materials, whose price is directly affected by fluctuations in world market prices (R2112-14). Outside that case, the contract is concluded at an adjustable price where the parties are exposed to major hazards arising from the reasonably foreseeable change in economic conditions during the period of performance (R2112-13). The formula has to use published indices, the building indices for building work and the civil engineering indices for infrastructure. An unpublished index makes the formula unenforceable.
ℹ The standard adjustment formula The general form is the revised price equals the original price multiplied by the sum of three terms: a coefficient times the movement in the building index for the main package, plus a coefficient times the movement in the wage index, plus a fixed part. The three coefficients add to one, and the fixed part is usually 0,15. For a concrete frame contract, use the reinforced concrete index. For an aluminium joinery contract, use the aluminium joinery index. The fixed part is a negotiated contractual value representing the share of overheads that is not indexed.
5. Changes during performance
This is the most critical point for the economist during construction. Article L2194-1 lists six cases in which a public contract can be changed without a fresh competition.
One, review clauses: a change provided for in the original contract, such as the price adjustment clause or an option written into the conditions. There is no ceiling where it was provided for at the outset.
Two, necessary additional works: additional works that have become necessary and were not originally foreseen, and that another operator could not carry out. The ceiling, for a contracting authority, is 50 % of the original contract value for each modification, price variation included (R2194-3 and R2194-4).
Three, unforeseen circumstances: a change made necessary by circumstances a diligent buyer could not have anticipated, site hazards, an archaeological discovery, unforeseen ground conditions. The ceiling is 50 % of the original contract value for each modification, for a contracting authority (R2194-3, applicable by reference from R2194-5).
Four, a new contractor (R2194-6): a new contractor may take the place of the original contractor under a review clause or an option, or following an assignment of the contract consequent on a restructuring of the original contractor, if that assignment does not entail other substantial modifications and is not intended to remove the contract from competition; the new contractor meets the conditions of participation set for the original contract.
Five, a non-substantial modification (R2194-7): whatever its value, a modification that is not substantial is possible. A modification is substantial in particular if it introduces conditions which, had they been included in the original procedure, would have attracted other operators or allowed another tender to be selected, if it changes the economic balance of the contract in the contractor's favour in a way that was not provided for, if it considerably changes the subject matter of the contract, or if it replaces the contractor outside case four. A modification made necessary by unforeseeable circumstances nevertheless falls under case three and its ceiling, even if it is not substantial (Conseil d'État, opinion of 15 September 2022, no. 405540, point 15).
Six, low-value modifications (R2194-8 and R2194-9): its value is below both the European threshold for works, 5 404 000 € excluding VAT since 1 January 2026, and 15 % of the original contract value; successive low-value modifications are cumulated, price variation included. There is no need to check that the modification is not substantial.
The third case can apply to site discoveries in refurbishment, such as residual asbestos or a decayed structure, where a diligent buyer could not have foreseen them. For a contracting authority, the limit is 50 % of the original contract value for each modification; beyond it a fresh competition is required, which is practically unworkable mid-contract.
6. Private against public: the key economic differences
| Dimension | Private contract | Public contract | What it means for the economist |
|---|---|---|---|
| Choosing the contractor | Free, criteria unpublished | Tender instructions compulsory, criteria weighted and published | The abnormally low tender procedure and the multi-criteria analysis follow strict rules |
| Form of price | Free: fixed, adjustable, lump sum | Governed by the code; adjustable price where there are major hazards during performance (R2112-13 and R2112-14) | The formula has to be in the conditions of contract from the moment the package is drafted |
| Changes | Free, by agreement | Six exhaustive cases (L2194-1) and the code's ceilings | An unlawful variation can be annulled, and justification is compulsory |
| Payment periods | Agreed in the contract; between professionals subject to the Code de commerce, no more than sixty days from the issue of the invoice, or forty-five days end of month if the contract expressly so provides, without manifest abuse (CCH, art. L124-2; Code de commerce, art. L441-10, I) | 30 days maximum, with interest running automatically | Valuations have to be settled within the statutory period |
| Completion | Free procedure | A regulated procedure with a certificate, snags and the making-good year | Completion starts the warranties; the procedure has to be followed |
| Disputes | The ordinary courts | The administrative courts, with distinct rules and time limits | Challenges follow a different procedure, to be anticipated |
| Advertising | Not compulsory | Compulsory above the thresholds, in the official journals and on the buyer's platform | Failing the advertising obligations annuls the procedure |
| Subcontracting | Free | Governed by statute, with direct payment of the subcontractor | The subcontractor can claim payment directly from the public buyer |
In summary
The code applies as soon as the buyer is a public body or an organisation charged with a public service mission. The eight articles that govern a works contract cover price and adjustment, selection criteria, abnormally low tenders, changes in six exhaustive cases (L2194-1), payment and interest, completion, splitting into packages, and the adjustment formula. The formula is compulsory where there are major hazards during performance (R2112-13), and beyond three months for contracts exposed to world market prices (R2112-14). Changes are limited to six statutory grounds, with a ceiling of 50 % of the original value per modification, for a contracting authority, in the case of unforeseen circumstances (R2194-3 and R2194-5). The key differences from private practice are weighted published criteria, a compulsory adjustable price, a 30-day payment period, automatic interest, and disputes heard in the administrative courts.
The nature of the figures quoted
Amounts and rates set by a text are quoted with their article and date. The other percentages and amounts on this page, dated reference points or a fictitious example, are orders of magnitude for framing, not measurements: they substitute neither for a tender exercise nor for an estimate prepared on drawings.
Articles liés
Sources: the BT construction cost indices published monthly by INSEE on its 2010 base, used to update the figures · construction cost statistics from SDES, the statistical service of the ministry responsible for construction · regulatory texts published in the Journal officiel and consolidated on Légifrance for the requirements cited.