1. What separates public procurement from private contracts
An economist moving from private to public work finds a radically different environment, not in the techniques of measurement and estimating, which are the same, but in the procedural frame around every decision.
Advertising and competition are compulsory: on a private contract the client chooses its contractors freely. On a public works contract, advertising and competition are required in principle once the estimated value of the need reaches 100 000 € excluding VAT: below that, the buyer may dispense with them (R2122-8, for consultations launched since 1 January 2026). Up to the European threshold for works, 5 404 000 € excluding VAT since 1 January 2026, the procedure can be adapted (L2123-1); above it, it is formal (L2124-1), with publication, response periods and published criteria.
Award on the published criteria: a public buyer cannot award to whom it likes. It is bound by the criteria and weightings published in the tender instructions, and any departure can be challenged in court.
A public accountant between client and contractor: on a private contract the client pays directly on the invoice. On a public one a public accountant approves each payment order, triggered by a certificate that the work has been done.
A statutory payment period with automatic interest: 30 days, with interest running automatically and no need for a formal demand. An economist who takes too long to check a valuation exposes the buyer to interest.
A strict final account procedure with binding deadlines: on a private contract the balance is negotiated. On a public contract that refers to the CCAG-Travaux 2021, the contractor notifies its draft final statement within 30 days of notification of the acceptance decision (art. 12.3.2). The design team accepts or corrects it, then draws up the draft final account (art. 12.3.3 and 12.4.1), which the client signs and notifies no later than 30 days after receiving the final payment request, the later of the dates of receipt by the design team and by the client being used (art. 12.4.2). The contractor has 30 days from its notification to return it signed, with or without reservations, or to give reasons for refusing it; after that period, or if no reasons are given, it is deemed accepted (art. 12.4.3 and 12.4.5).
Changes limited to the statutory cases: on a private contract a variation can settle anything. On a public one, a modification of the contract without a new competition, by variation or, for an administrative contract, by unilateral decision of the buyer, is possible only in one of the six cases of article L2194-1; for a contracting authority, additional works that have become necessary and modifications due to unforeseen circumstances are capped at 50 % of the original contract value for each modification (R2194-3 and R2194-5).
2. The economist's role stage by stage
| Stage | Main duty | Deliverables | Risk if absent |
|---|---|---|---|
| Brief and feasibility | Produce the economic order of magnitude and check the budget against the brief | A preliminary estimate from rates, an economic feasibility note | An inadequate budget authorised, a brief that cannot be afforded |
| Outline and developed design | Refine the estimate by element and check it against the funding approved | A developed design estimate by package with contingency, a cost dashboard | Drift undetected, underfunding discovered at tender assessment |
| Tender documents | Produce the financial documents and check them against the specification | A priced bill with rates updated by the published indices, a model pricing schedule, the adjustment formula, the procedural thresholds | An inconsistent package, tenders that cannot be compared, abnormalities undetectable |
| Tender assessment | Compare the tenders financially, identify abnormally low ones, produce the report | A multi-criteria comparison schedule, the statutory procedure where it applies, a complete report | An award to an abnormally low tender, failure on site, extra cost for the client |
| Construction | Check the monthly valuations, calculate the adjustment, track the budget | Verified valuations, the adjustment calculation, a budget and variations dashboard | Wrong payments, adjustment never calculated, an overrun nobody saw coming |
| Completion and after | Prepare the draft final account for the design team, or check it for the client, who signs and notifies it (CCAG-Travaux 2021, art. 12.4.1 and 12.4.2), check it against the valuations and variations, track the making-good year | A complete final account with adjustment, damages and retention, plus a snagging dashboard | A contested account, snags untracked, retention released too early |
Tender preparation and tender assessment are the two decisive stages, because they are where the economist's intervention most affects the final quality of the contract. A badly prepared package, an out-of-date priced bill, no adjustment formula, a pricing schedule inconsistent with the specification, creates problems at every later stage. An inadequate tender report exposes the buyer to a challenge that can annul the award.
3. The fifteen operational reflexes
These are not theoretical rules but concrete checks that prevent the commonest and most expensive errors on public works contracts. Four of them are critical, because omitting them has irreversible consequences.
| # | Reflex | When | Related subject |
|---|---|---|---|
| 1 | Check the procedural threshold before drafting the tender package | Starting the package | Thresholds and procedures |
| 2 | Check that the works are split into packages, and justify any departure in writing | Before the package | Splitting into packages |
| 3 | Produce a priced bill with rates updated by the published indices, not rates three years old | Tender documents | Tender documents and adjustment |
| 4 | Draft the adjustment formula in the conditions of contract, with indices matching each package | Tender documents | Price adjustment |
| 5 | Publish the price scoring formula in the instructions, not merely the weighting | Tender documents | Tender assessment |
| 6 | Identify abnormally low tenders before award and trigger the statutory procedure | Tender assessment | Abnormally low tenders |
| 7 | Justify each technical mark with an explicit sentence in the report | Tender assessment | Technical submissions |
| 8 | Check the structural warranty certificates of every contractor before the start instruction | Before commencement | Warranties |
| 9 | Check the list of subcontractors before the first payment | At commencement | Subcontracting |
| 10 | Calculate the price adjustment on every valuation; do not defer it to the final account | Monthly valuations | Price adjustment |
| 11 | Warn the client in writing as soon as cumulative variations pass 10 % of the original contract, a method alert threshold and not a legal cap: in works, only low-value modifications are capped cumulatively, at 15 % of the original contract and below the European threshold (R2194-8 and R2194-9) | During the works | Cost control |
| 12 | Prepare, for the design team, the draft final account as soon as the draft final statement is received: the client must notify the final account within 30 days of receiving the final payment request (CCAG-Travaux 2021, art. 12.4.1 and 12.4.2), not six months later | Completion | Final account |
| 13 | Accept the works with snags where there is any doubt: a snag can be cleared, it cannot be created later | Completion | Completion |
| 14 | Track the making-good snagging dashboard monthly | The making-good year | Warranties |
| 15 | Release the retention as soon as the snags are cleared; do not hold it without reason | After completion | Retention |
Reflexes 1, 6, 8 and 13 are the critical ones, because omitting them can have irreversible consequences: an unlawful procedure, a contractor failure that was not spotted, a client uninsured for ten years, or the loss of the right to withhold. The others concern errors that are recoverable, sometimes expensively, but recoverable.
4. Refurbishment against new build in public works
Most public works contracts today are refurbishment: energy retrofit of the school estate, accessibility compliance, ordinary maintenance of public buildings. Those contracts have economic specifics the economist has to reflect.
Uncertain quantities: preliminary investigations do not reveal everything, and the real quantities can diverge significantly from the estimate. A schedule of rates is indispensable for valuing the additional work on contractual rates.
Unforeseen circumstances (R2194-5): in refurbishment, site discoveries (unmapped asbestos, decayed structure, unidentified services) can justify a variation if a diligent buyer could not have foreseen them; for a contracting authority, each modification is capped at 50 % of the original contract value (R2194-3).
Partial occupation during the works: refurbishment contracts in occupied buildings, a school, a town hall, a care home, need phasing written into the specification, with access constraints, working hours and measures to protect the users.
Asbestos removal beforehand: for buildings from before 1997 a survey before works is compulsory. Removal can represent 5 to 15 % of the total budget, and it belongs in the pre-tender estimate rather than being discovered when the site opens.
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
- The public procurement code and works contracts: what the economist needs to know
- Tender documents in public works: pricing schedules, rates and the financial papers
- Procurement thresholds and procedures: negotiated, open tender and the selection criteria
- Assessing public tenders and abnormally low offers
- The technical submission: what the buyer scores and what the contractor should write
- Price adjustment in public works: the parametric formula, the indices and the calculation
- Standard works contract conditions: the economic clauses to master
- Pre-tender estimates and cost control in public procurement
- Splitting works into packages and coordinating them in public contracts
- Payment and final accounts in public works
- Subcontracting and warranties in public works: what the economist must check
- Construction economics: the complete guide for professionals
- Construction costs in France: rates per m², building types and the factors that move them
- Energy retrofit: costs by measure, grants available and the return on investment
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.