Statutory increases, price revision and the budget's base date

The budget, the estimate and the tenders are not drawn up at the same time, and each has its own base date. Comparing them without bringing them back to a common date means attributing to the client's decisions what is merely an effect of time.

Amount	Base date	Legal basis
Client's budget	the one the client sets and writes down (architect's agreement, council resolution)	contract, decision of the competent body
Contracting authority's estimate (devis)	when the notice is sent or, where there is no notice, when the procedure is launched	law of 8 April 2018, art. 12, § 5, c)
Tender prices	the prices used in the analysis are those valid on the day the tenders are opened	Grand-Ducal regulation of 8 April 2018, art. 36
Final cost	after acceptance, revisions included	law of 8 April 2018, art. 47

The first date is the only one the client fully controls. That is why it must appear in the agreement with the architect, alongside the amount and the scope: the article on writing the budget into the architect's agreement covers this point. A budget set at the start of design and a tender launched several months later do not reflect the same price level; the difference must be quantified and explained before the tenders are opened, not discovered afterwards.

Updating a budget from one date to another relies on published indices. The choice of index and how to read it are covered in the article on the index and price revision, and the relevant statistical publications in the one on official price sources. No index value is given here.

The term appears in article 47 of the amended law of 8 April 2018 on public procurement. Its paragraph 2 provides: "Where the estimate or the agreed price is exceeded, the statutory increases are to be shown separately" (unofficial translation). Its paragraph 3 adds: "A justification is to be provided for all overruns exceeding the statutory increases." Article 48 repeats the same distinction for major State works, whose final account is sent to the Chamber of Deputies.

The consequence for the client is direct. The final account will separate what results from price movements provided for in the contract from what results from other causes (modifications, quantities, estimating errors). Only the second part has to be justified. Tracking that does not separate the two from the start makes that justification hard to produce.

The texts read do not define the term. Under article 110 of the implementing regulation, price adjustments "constitute price revisions". The reading adopted here, which is not a legal definition, treats as statutory increases the effect of the price revisions and adjustments provided for by the contract and the regulation.

The starting rule fits in one sentence of article 35 of the implementing Grand-Ducal regulation of 8 April 2018: "The special specifications determine the price revision method". It is therefore when drafting the tender documents that the client decides how price movements will feed into its final cost. Two regimes coexist.

First regime: a calculation formula in the special specifications (cahier spécial des charges). The regulation allows formulas to be set out there; in that case, they displace the adjustment-on-request regime of article 109, paragraph 1, and articles 110 to 118. The cost of revision then becomes calculable in advance, from the chosen indices. The usual formulas and how to set them up are covered in the article on price revision.

Second regime: adjustment on request, where there is no formula. Article 109 allows an adjustment in the event of unforeseeable variations in prices or wages resulting from legal or regulatory measures, or of significant and unforeseeable fluctuations in official quotations. The request is reasoned and sent by registered letter, and takes effect on receipt, except for officially published variations and wages (art. 111 to 113).

Rule of the adjustment regime	Content	Article of the regulation
No retroactivity	no adjustment for services performed before the request	art. 117
Wage threshold	0.5% of the work remaining for wage adjustments	art. 117
Materials threshold	2% of the total value of materials, assessed per subcontractor under a general contractor	art. 117
Contractor delay	indices at the contractual due date, unless indices more favourable to the contracting authority apply	art. 118
When it is taken into account	in the final account, with interim payments on revision possible under conditions	art. 116

When payment happens matters as much as the amount. Article 116 provides that "price adjustments are taken into consideration only at the time of the final account". Interim payments on revision remain possible for contracts above EUR 50,000 (index value 100), where the interim payments exceed EUR 2,500 (same basis), against a guarantee. Both amounts are expressed in index value and have to be updated; their current value is not given here. For the client's cash flow, this means that part of the statutory increases may only appear at the end, even though it relates to work carried out much earlier.

Delay has a price too, but not always for the client. Where the delay is attributable to the contractor, article 118 freezes the indices at the contractual due date, unless indices more favourable to the contracting authority apply. A dated contractual programme should therefore be kept alongside the dashboard.

Revision interacts with the modification ceilings. Where the contract includes an indexation clause, article 43, paragraph 3, of the law makes the updated price the reference value for assessing the limits on modifications: the percentages for amendments are calculated on that basis. Amendments themselves are covered in the article in this branch devoted to them.

Extreme variations fall under a different mechanism. Article 44, paragraph 4, of the law allows either party to terminate the contract in the event of significant and unforeseeable variations in prices, wages or conditions of performance following a case of force majeure. This is no longer a question of revision but of the contract's survival.

Regulatory news in 2026 is worth following. A communication of 1 July 2026 to contracting authorities, published on the public procurement portal, concerns "price increases and the availability of materials". Its content and scope are presented in the article on price revision in the specification guide, cited above.

On the dashboard, statutory increases have their own line, separate from amendments. It holds three amounts: revision already invoiced, revision projected on the remaining work, and, under the adjustment regime, requests received but not yet accepted. The dashboard is presented in the article on tracking the final cost during the works.

Three bookkeeping rules avoid confusion. Record, for each contract, the revision method set in the special specifications and the base date of prices. Project the revision to the end of the contract, rather than stopping at the amounts invoiced. Never offset a statutory increase against a saving on another item within the same line: the offset shows in the final cost forecast, not in the line. This discipline directly prepares the separate column that the final account against the estimate will require.

The Civil Code lays down the opposite rule to that of a revisable contract. Under article 1793, a contractor who has undertaken to construct a building for a lump sum, on the basis of a plan settled and agreed with the owner of the land, cannot claim any price increase because labour or materials have become more expensive. Only a revision clause in the contract changes that rule.

A private client therefore decides how the risk is shared. Accepting a revision clause means accepting a "revision" line on the dashboard, which will have to be dated and projected as in a public contract. Refusing it means letting the contractor build that risk into its initial price. Either way, the base date of prices must appear in the contract.