The distinction
The definition is a negative one, and the rest of the system follows from that. Whoever knows the catalogue of basic services thereby knows the field of additional services.
| Basic services | Additional services | |
|---|---|---|
| Definition | allocated to the work phases in the service profiles | all other services |
| Catalogue for buildings and interiors | Annex 10 | examples in the same annexes |
| Covered by | the fee under the percentages of the phase | to be agreed and paid separately |
| Exhaustive? | yes, for the basic services | no, the list is open |
Two peculiarities apply, and both widen the field of what can be paid separately. Both argue for supplementing the catalogue in the contract rather than relying on the annex.
| Peculiarity | Consequence |
|---|---|
| The annexes contain only examples | a service not listed there may still be an additional service, provided it is allocated to no phase as a basic service |
| They are not tied to a work phase | they may be agreed for service profiles and phases to which they are not allocated, so long as they are not basic services there |
What applies without a valid agreement
An important difference from basic services runs here, and it is frequently overlooked. It concerns not the claim but its enforceability.
| Basic services | Additional services | |
|---|---|---|
| Without agreement in text form | base fee rate applies as agreed | customary remuneration under general contract law |
| Legal basis | § 7 paragraph 1 HOAI | § 632 paragraph 2 of the German Civil Code |
| Amount | derivable from the fee table | must be pleaded and proved in a dispute |
For basic services a fallback rule therefore applies with a quantifiable result. For additional services, customary remuneration applies, whose level the designer must establish in a dispute.
That is the practical reason additional services more often go unpaid than basic ones: not because no entitlement exists, but because it is harder to enforce. The burden of proof lies with the designer.
The typical disputes
Three situations recur. All three arise because the classification of the service was not settled in advance.
| Dispute | What actually applies |
|---|---|
| The service is taken for a basic service | the annex catalogue governs, and it is exhaustive for the basic services |
| The service is performed without notice | a claim to payment does not arise automatically; the client must have commissioned the service |
| The service arises from a change | whether it is an additional service or triggers an adjustment of the fee for basic services must be examined separately |
The boundary in cases of change is covered in the article on changes of scope. That article also sets out the two conditions that must be met cumulatively.
Which services are most often overlooked
The following are regularly performed without separate agreement. Their classification in any given case depends on the service profile and must be checked.
| Service | Why it is overlooked |
|---|---|
| The cost framework | it arises in needs planning, before or at the start of basic evaluation, and is not a basic service; at the same time the most consequential cost statement of the project |
| Deepened cost determinations | a cost calculation beyond the depth owed, for instance by individual items or execution types |
| Options appraisals beyond the scope owed | the service profiles provide for examining solutions in several phases; anything beyond that is paid separately |
| Measured survey and condition recording in existing buildings | recording the existing condition is substantial effort and does not belong to the basic services as a matter of course |
| Evidence and specialist contributions | energy certificates, certification support, fire safety concepts: depending on the contract an additional service or a separate specialist design |
Why the distinction has gained weight
Since binding price law fell away, the distinction between basic and additional services has gained weight, for a reason that seems paradoxical at first. Less price law means more service law.
While the fee tables bound the parties, disputes were mostly about the level: which rate applies, which zone is relevant, was the minimum rate observed. Today the level is freely negotiable, and the dispute shifts to the question of what is actually owed for the amount agreed.
The service profiles in the annexes have thereby become the most important normative reference in the contract. They are the only normed catalogue of what a work phase comprises, and they serve as the measure even where a lump sum fee has been agreed.
For contract drafting a reversal of priorities follows: precisely describing the scope now matters more than deriving the amount. A tightly defined scope at a freely agreed price is more enforceable than a table-conforming price for an unclear scope.
How additional services should be agreed
Four points belong in the agreement, and they cost little to prepare. The fourth is particularly often overlooked with additional services, because they are frequently agreed late and informally.
| # | Point | Content |
|---|---|---|
| 1 | Name the service | using the wording of the annex where it is listed there |
| 2 | Fix the remuneration | lump sum, time charge or percentage; freely agreed, hard to enforce without a provision |
| 3 | Record the trigger | for services arising during the project; a framework agreement with hourly rates is more workable than a negotiation mid-project |
| 4 | Observe the form | for consumers the duty to give notice applies to every kind of remuneration agreement, including hourly rates and lump sums |
The fourth point is especially often overlooked for additional services, because they are frequently agreed later and informally. The system is covered in the article on fee agreements.
Give notice before performing
The most effective single measure is also the simplest: before performing, state in text form that the work is an additional service, and wait for the commission. It costs one email.
This is not a legal device but a question of sequence. Work performed and then invoiced leads to an argument about whether it was commissioned. Work offered and commissioned before performance leads to an invoice.
For practices with repeat clients, listing the catalogue of additional services with prices within the proposal has proved useful, even where they are not commissioned at that point. Commissioning them later then becomes a call-off decision rather than a negotiation.
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This article reflects the position of the rules and case law at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.