The mandatory estimate in a public contract

The estimate is mandatory. The Act of 17 June 2016 on public procurement (a federal law, applicable in all three regions) provides that the value of the contract must be estimated (art. 16). The pouvoir adjudicateur (contracting authority), within the meaning of article 2, 1°, of the same law, bears that responsibility, even when it entrusts the calculation to its designer.

It is expressed excluding VAT. The same article specifies that, "unless otherwise provided, all amounts in this law are understood excluding value added tax" (unofficial translation, as are all quotations of Belgian texts in this article). All the thresholds cited on this page are therefore amounts excluding VAT, and the estimate must be compared with them without VAT. VAT in the budget is dealt with separately, according to the rules set out in the article on VAT.

It comes before the choice of procedure. It is the estimate that shows which procedure is open to the contracting authority. It is therefore made when the documents are advanced enough to be priced, and not afterwards to justify a choice already made.

Each threshold is a switch. The following amounts are those read on Justel on 21 October 2026, in the Act of 17 June 2016 and in the Royal Decree of 18 April 2017 on the award of public contracts in the classic sectors.

Amount (excl. VAT)	Procedure available	Basis	What it allows
Below €30,000	low-value contract	Law, art. 92	conclusion by accepted invoice
Expenditure to be approved below €140,000	procédure négociée sans publication préalable (negotiated procedure without prior publication)	Law, art. 42, § 1, 1°, a); RD, art. 90, 1°	consultation, where possible, of several economic operators, and negotiation
Works with an estimated value below €750,000	procédure négociée directe avec publication préalable (direct negotiated procedure with prior publication)	Law, art. 41, § 1, 2°	the contracting authority "may negotiate"
€5,404,000 and above for works	European threshold	RD, art. 11	the contract falls under the rules applicable above the European thresholds

Two different wordings, not to be confused. Article 41 refers to works whose "estimated value" is below €750,000; article 42 refers to "expenditure to be approved" below the amount set by the King, namely €140,000 excluding VAT according to article 90, 1°, of the Royal Decree. In the second case, it is the amount that will be approved that counts: an estimate that is too tight exposes the contracting authority to discovering, when the tenders are opened, that the chosen procedure did not suit the actual expenditure.

The possibility of negotiating depends on the procedure, and therefore on the estimate. The procedures in which negotiation is permitted, and their conditions, are covered in the article on when the procedure allows negotiation. For the estimate, there is only one consequence: a contract estimated above a threshold loses access to the procedure below it.

Lots are counted together. The Royal Decree also allows the negotiated procedure without prior publication for lots below €100,000, under conditions, in a contract whose estimated value is below the European thresholds and provided that the combined value of those lots does not exceed 20% of the estimated value of the contract (art. 90, 3°). That option presupposes an estimate of the whole contract, and not only of the lot concerned.

The names of the procedures already indicate the level of publicity. The negotiated procedure without prior publication does without a contract notice; the direct negotiated procedure with prior publication requires one; above the European threshold, publicity changes scale.

A wrong choice of procedure is not repaired by a better tender. If the estimate leads to a procedure that was not open for the value of the contract, the question is no longer one of budget but of law: the procedure itself is called into question. That is why the estimate must be documented when the procedure is chosen, with its assumptions and its date.

The estimate becomes the yardstick for the tenders. The law requires prices to be checked (art. 84), and the Royal Decree sets the order: correction of errors (art. 34), checking of the prices or costs of all tenders (art. 35), then examination of prices that are "abnormally low or high" (art. 36). A price only appears abnormal against a reference: the estimate, item by item, is the first of these.

An overall estimate is not enough for this exercise. The examination under article 36 covers non-negligible items as well as the total amount. An estimate detailed by item makes it possible to spot an abnormal unit price, to ask for written justification (the decree sets a time limit of 12 days) and to give reasons for the decision. An estimate reduced to an overall amount does not.

The award follows. The contract is awarded to the most economically advantageous tender (art. 81). The estimate does not determine that choice, but it tells the contracting authority whether the most advantageous tender fits within the approved budget.

Price adjustment also depends on the estimated value. The general implementing rules (Royal Decree of 14 January 2013) make price adjustment compulsory in works contracts, except where the estimated value is below €120,000 and the initial period is below 120 working days or 180 calendar days (art. 38/7). The estimate therefore also determines whether the budget must include a contractual price adjustment.

Underestimating means condemning oneself to receive tenders above the estimate. The contracting authority then faces a choice it could have avoided: abandon, negotiate if the procedure allows it, or start again. The law allows this, since "completing a procedure does not imply an obligation to award or conclude the contract" (art. 85), but each relaunch costs months and administrative expense. These options are covered in the article on tenders above the estimate.

Underestimating also distorts the procedure. An estimate below a threshold, when the actual expenditure exceeds it, leads to a less demanding procedure than the one that was required. The problem appears at the worst moment, when the tenders are on the table.

Overestimating is no more prudent. An inflated estimate can impose a heavier procedure than necessary, widen publicity without reason, and above all mask abnormally high prices: an overpriced item does not stand out against a reference that is itself too high.

A good estimate is neither cautious nor optimistic: it is dated, detailed and justified. The contracting authority's budget can contain a contingency; the contract estimate, for its part, must reflect the probable price of the works described.

Start from the tender quantities. The estimate is calculated on the quantities in the métré (meetstaat, bill of quantities) that will be given to tenderers, with the same items. The rules specific to the bill of quantities in public contracts are covered in the article on measurement in Belgian public contracts.

Date the prices. An estimate without a price month is comparable to nothing. If several months separate the estimate from the submission of tenders, update it before launch, and record the date used.

Write down the assumptions. Prices drawn from which comparable contracts, what allowance for the size of the project, what access conditions, which items estimated by ratio for lack of detail. These assumptions serve twice: to justify the choice of procedure, and to read the tenders.

Check the estimate received. A contracting authority that receives its architect's estimate checks it as a private client would: same quantity base, same price date, same items. The method is set out in the branch article on checking the architect's estimate. A second, independent estimate is useful when the value lies close to a threshold.

Keep everything on file. The estimate, its assumptions, its date and any updates form the record that will justify, if necessary, the choice of procedure and the decision to award or not. The following table summarises what each element contributes.

Element	Why it matters	Where it will be used again
Total amount excl. VAT	choice of procedure and publicity	decision to launch
Breakdown by item	spotting abnormal prices	checking of prices (RD, art. 35 and 36)
Price date	comparability with the tenders	tender evaluation report
Written assumptions	justification of the estimate	decision to award or not to award
Estimate by lot	use of the option in art. 90, 3°	choice of procedure by lot