Why the budget comes before the drawings
The architect designs within a framework the client provides. The code of ethics of the Ordre des architectes (Order of Architects) of 16 November 2022 (art. 16) requires designs to be submitted "within the limits of the brief set in the appointment and of the budget" (unofficial translation). The text therefore assumes a budget that exists and is known to both parties.
A budget that arrives after the drawings no longer works as a limit. It becomes an observation: the client either accepts the amount or has the design reworked, with a new delay.
The same article provides a second lever. Any change to the brief "must be the subject of an additional agreement stating its financial impact". This mechanism only works if the initial brief and its budget are in writing: without a starting point, no impact can be measured.
The five decisions that make the budget defensible
Setting a budget is not announcing a figure. It means taking five decisions that can be reread in the event of a disagreement.
| Decision | Question to settle | What it prevents |
|---|---|---|
| Scope | works budget or total project cost? | comparing an estimate with an envelope that does not cover the same items |
| Value date | in which month is the amount expressed? | confusing a price rise with an overrun |
| Contingency | what reserve, for which risks? | using up the margin without knowing it |
| Region | where is the project located? | applying the requirements of another region |
| Writing | where does the budget appear? | an oral budget, hard to prove |
Works budget or total cost
The works budget is only part of what the project costs. Fees, health and safety coordination, the PEB (energy performance) assignment, insurance, utility connections, planning charges, VAT and finance costs come on top. The client must say which of the two amounts is given to the architect: the clearest approach is to give the works budget, excluding VAT, as the design limit, and keep the total cost as the client's own limit. The step from one to the other is covered in the article from works budget to total project cost, and the items most often forgotten in what a price per m² never includes.
Starting from a price per m² is fine, provided it is converted. A ratio gives an order of magnitude, not an envelope; the method is set out in the article from price per m² to total budget.
Dating the budget
An amount without a value date can be compared with nothing. Prices move between setting the budget and receiving tenders. Writing "works budget expressed at the value of a given month, excluding VAT" later makes it possible to separate the effect of prices from the effect of the project.
Setting an explicit contingency
The contingency must be a line in the budget, not an implicit margin. If it is hidden in the unit prices of the estimate, nobody knows when it is used up. If it is written down, with the risks it covers, it can be tracked and released stage by stage.
Naming the region
Planning law and energy are regional matters. The permit, energy performance requirements and planning charges are not the same in Brussels, Wallonia and Flanders. A budget set without a region implicitly borrows the rules of another.
Writing the budget into the architect's agreement
The right place is the architect's agreement. The 2022 code (art. 20) requires a written agreement "at the latest when the appointment has been defined". That is the moment the budget must go into it, with its scope, its value date and its contingency.
Involving an architect is compulsory for works that need a permit, subject to exemptions (Act of 20 February 1939, art. 4, a federal law applicable in all three regions). The client therefore cannot sidestep the question: an agreement will be signed in any case, so it may as well carry the budget.
Three entries are enough to make the budget useful: the amount and what it covers; the value date; and the rule that any change to the brief requested by the client is the subject of a priced additional agreement. What weakens the client later is a budget that stayed oral and changes to the brief that were never recorded.
The articles in this branch
- The article on moving from works budget to total project cost covers the items outside the works, who invoices them and when each one becomes certain.
- The article on contingency by project stage covers the three reserves not to be confused and how they are released from one stage to the next.
- The article on how the region changes the budget covers the items that vary between Brussels, Wallonia and Flanders, and those that remain federal.
This article sets out the rules as at 21 October 2026 and is intended for professional orientation. It replaces neither legal advice nor an examination of the specific case.