The six stages at a glance
| Stage | Basis | Depth of detail | Timing |
|---|---|---|---|
| Kostenrahmen (cost framework) | briefing | first level | work phase 1 |
| Kostenschätzung (cost estimate) | concept design | second level | work phase 2 |
| Kostenberechnung (cost calculation) | developed design | third level | work phase 3 |
| Kostenvoranschlag (pre-tender estimate) | construction preparation | third level or procurement packages | work phase 6 |
| Kostenanschlag (tender sum) | procurement and construction | by the packages set in the pre-tender estimate | work phase 7 |
| Kostenfeststellung (final cost statement) | verified invoices | third level | work phase 8 |
Four of these stages are carried out once at a defined point in the project: cost framework, cost estimate, cost calculation and final cost statement. The pre-tender estimate, by contrast, may be prepared either once or repeatedly and in several steps.
Why many sources list five stages
The Kostenvoranschlag was introduced with the December 2018 edition. In substance it corresponds to the former Kostenanschlag but now precedes it, serving decisions on procurement and construction. The Kostenanschlag moved later and was narrowed to determination on the basis of tenders, orders and costs already incurred.
A considerable share of the material available online predates that change or was never updated, and still lists five stages. Anyone relying on such a source misses precisely the stage sitting at the interface between design and procurement. The distinction is covered in the article on pre-tender estimate and tender sum.
The required depth was tightened in 2018
Less visible but practically more consequential than the new stage is the deepening of the required treatment. It demands a deeper level of structure at each stage than before.
| Stage | Depth formerly | Depth since 2018 |
|---|---|---|
| Cost estimate | first level | second level |
| Cost calculation | second level | third level |
The same applies here: numerous sources, older templates and software defaults still carry the former requirements. A cost estimate showing only the eight first-level cost groups no longer satisfies the current edition.
Notably, the HOAI did not follow this deepening. It requires the cost calculation to be prepared to at least the second level. Anyone calculating to the third level in conformity with the standard potentially delivers more than the basic service requires. That question belongs before contract and is covered in basic services versus additional services.
The tolerance figures do not come from the standard
Almost every treatment of this subject quotes accuracy figures by stage: plus or minus 30 per cent for the cost estimate, 20 per cent for the cost calculation, 10 per cent for the tender sum. They are routinely attributed to DIN 276.
The standard does not contain these values. It describes the stages by purpose, basis and degree of detail, but prescribes no permissible deviation. The percentages in circulation are values drawn from practice and professional literature.
That is no reason to discard them. They convey the order of magnitude of uncertainty at each design stage accurately and are usable in discussion with a client. It is a reason not to cite them as a requirement of the standard.
The question of permissible deviation becomes legally relevant elsewhere in any case, namely in liability for an incorrect cost determination. Court decisions provide orientation there, and the ranges cited sit closer together, at roughly 15 to 25 per cent, than the circulating rules of thumb suggest. The individual case governs.
For your own practice it follows that any accuracy figure written into a cost determination should be identified as a value drawn from experience rather than as a requirement of the standard. Contingencies and tolerances are covered in cost risks, contingencies and tolerances.
The three early stages
The cost framework arises during briefing and serves the decision on the project itself. It is the earliest and simultaneously most consequential cost statement, because it is later used as the yardstick. It is not a basic service under the HOAI.
The cost estimate arises from concept design and serves the decision on that design. It is the first stage owed as a basic service.
The cost calculation arises from developed design. It is the most important stage of the whole project, not because of its accuracy but because of its function: the fee for all basic services is derived from it.
Both early stages are covered in the article on cost framework and cost estimate, the cost calculation in cost calculation at the third level. It also sets out which items come out systematically low in early determinations.
The three later stages
The pre-tender estimate determines costs from construction preparation and prepares procurement. It additionally orders costs by procurement package.
The tender sum compiles tenders, orders and costs already incurred. No estimated costs may remain within it. It follows the package structure set in the pre-tender estimate.
The final cost statement evidences the costs actually incurred from verified invoices. It closes cost planning and simultaneously opens the next cycle, since it supplies the benchmarks for future projects. That analysis is covered in the article on the final cost statement.
Net or gross
The standard permits both presentations. It requires only that the form chosen be stated.
The choice is not immaterial in practice. A client able to reclaim input tax works net; a private residential client bears value added tax as a cost component. For chargeable costs under the HOAI the question is settled: value added tax is expressly not part of them.
Anyone preparing a cost determination should therefore keep the form consistent across every stage and carry value added tax as a separate line. Switching between stages makes cost control impossible.
Ordering criteria alongside the cost structure
Structuring by cost group is the base structure but not the only ordering by which a determination can be built. The standard expressly provides for further ordering criteria that may be carried in parallel.
| Ordering criterion | Purpose |
|---|---|
| Cost groups by building element | base structure, comparability with benchmarks |
| Procurement packages | preparing tendering and award |
| Execution types and trades | allocation to the contractors |
| Construction phases and sections | control where delivery is phased |
What matters is that these orderings supplement rather than replace one another. A determination carried solely by procurement package loses comparability with published benchmarks and complicates the determination of chargeable costs. One carried solely by building element cannot be transferred directly into tender documents.
The workable solution is to retain the cost group structure as the leading one and carry the further criteria as additional allocations. The article on trade-oriented cost structure covers that variant in detail.
What the stages do not cover
DIN 276 captures the costs of the construction project, that is the investment. It does not capture the costs arising after handover: operation, maintenance, cleaning, energy and eventual removal. Those costs in use are the subject of a separate standard.
The separation is clean, but it creates a gap in the basis for decisions. Many early design decisions shift costs between investment and operation, for instance on insulation thickness, plant strategy or material choice. An appraisal knowing only the stages of DIN 276 assesses such decisions one-sidedly.
How the standards relate to one another is covered in DIN 276, DIN 277 and DIN 18960 compared. It also sets out which confusions arise most often.
The link to cost control
The stages do not stand side by side but build on one another. Between them sits cost control, that is comparison of each new determination against its predecessor.
A requirement follows for how each individual stage is built: the structure must remain comparable across the stages. Changing the ordering structure between two stages, for instance from an element structure to one by procurement package, interrupts cost control unless a reconciliation is carried alongside.
How cost control and cost management interact is covered in the branch on cost control and cost management. It also sets out how late an intervention can still have effect.
Related articles
This article reflects the position at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.