What case law makes of cost expectations
Even a rough budget figure counts for the architect. According to the BGH judgment of 21 March 2013 (VII ZR 230/11, reported from the court's press release), the architect must, together with the client and as early as the Grundlagenermittlung (establishing the basis of the project), "set out the economic framework for a building project and take into account the client's cost expectations" (unofficial translation). These expectations are "relevant even if they do not contain a precise upper limit for the building sum".
Doubts are for the architect to clear up, not the client. The same decision holds that the architect must clarify any doubts about the extent of the cost framework, and that the cost expectations "as a rule become part of the contract" if the architect does not object. This is the trend of published decisions, not a guarantee: anyone relying on it must later be able to prove the cost expectation.
Hence a simple rule. A budget only mentioned in conversation is hard to prove; a budget handed over in writing with the design commission is not.
The four items of a workable budget
An amount alone is not yet a budget. For the designer to keep to it, and for the client to compare it later with a cost determination, it needs four items.
| Item | Question | Typical mistake |
|---|---|---|
| Amount | How much is available? | a range instead of a figure |
| Scope | Which cost groups are included? | "construction costs" with no indication of whether external works, fittings or ancillary costs are included |
| Base date | Which price level does the amount refer to? | no date, so no comparison with later tenders |
| Tax | Gross or net? | the client thinks gross, the designer calculates net |
Scope determines comparability. A budget for the building and a budget for the whole project with land, ancillary construction costs and financing are two different figures. How to get from one to the other is covered in From the works budget to the client's total budget.
A benchmark is not a budget. A client deriving a budget from cost benchmarks per square metre must know which floor area and which cost groups the benchmark covers. This is explained in the article on reading construction cost benchmarks; this branch publishes no values of its own.
The right moment: before the design commission
The budget belongs in the architect's contract or an accompanying letter. Handed over later, it meets a design that has already fixed floor areas and standards.
The reference texts come in at different points. While essential design and supervision objectives are not yet agreed, the BGB (Bürgerliches Gesetzbuch, the German Civil Code) requires the architect to submit a planning basis with a "cost assessment for the project" for approval (section 650p(2) BGB). The HOAI (the fee regulations for architects and engineers) has no basic service on costs in work phase 1; the first is the "cost estimate in accordance with DIN 276, comparison with the financial framework conditions" in work phase 2 (Annex 10 HOAI). The Kostenrahmen (cost framework) under DIN 276 is a third instrument, explained in the article on the cost framework and the cost estimate. This means that only the client can supply the "financial framework conditions" against which the cost estimate is compared.
A strict cap or a target figure
The second decision is how binding the figure is. On the trend of published case law, failing to meet a Baukostenobergrenze (construction cost cap) agreed as a quality of the architect's work makes the design defective (BGH, judgment of 13 February 2003, VII ZR 395/01). Under the same decision, a tolerance only comes into consideration if the contract indicates that the sum is not meant to be a strict limit.
| Strict cap | Target figure | |
|---|---|---|
| Wording | expressly as a cap, with no tolerance | as an amount to aim for |
| Effect | exceeding it can amount to a design defect | the designer must respect it and report deviations |
| Suitable for | fixed financing, funding with a ceiling | projects with room for manoeuvre in the brief |
| Client's duty | align the brief with it, record changes in writing | approve deviations deliberately |
How the cap is worded and proved is covered in Agreeing a construction cost cap in the architect's contract. This branch gives no figures for tolerances, because case law on the point is inconsistent.
Public clients have their own model. For its building projects, the federal government sets a Projektkostenziel (project cost target), which the RBBau (the federal building guidelines) calls the "decisive control parameter". It is an object lesson for any client building a budget with a risk reserve and release rules.
The articles in this branch
- From the works budget to the client's total budget: which items belong in the budget besides the building, in what order they become certain and who puts a figure on them.
- Agreeing a construction cost cap in the architect's contract: the amount, scope, base date, binding force and change procedure of a cap, and the burden of proof under case law.
- The project cost target: how the federal government sets its building budget: the components of the project cost target under the RBBau, the release of risk costs and what private clients can take from it.
This article reflects the state of legislation, guidelines and published case law on 21 October 2026 and is intended for professional guidance. It is not a substitute for legal advice or for an examination of the individual case.