An interested party initially offers an amount for your German plot of land and, in addition, more money if a specific approval or other event occurs later. The advertised total sum looks attractive. For your decision, however, you should understand the actually secured portion and the conditional additional payment separately. The article does not draft any clause and does not assess any concrete likelihood of approval.
Break the promised sum down into its conditions
Our editorial recommendation: Write down which amount is to depend on what. How is the event described? Who could determine its occurrence? Which actual actions would be necessary for that and who is to initiate them? The formulation “if more is possible” is too vague as a basis for advice.
Also note the timing, the intended proof and the handling of project changes as open questions. A buyer’s wish for greater development is not automatically an attainable or owed approval.
Do not confuse different conditional models
§ 158 BGB distinguishes between suspensive and resolutive conditions with regard to the legal effect dependent on them. [BGB-158] How a particular purchase price arrangement operates and what security or form it requires cannot be deduced from that alone. This examination belongs in the actual full contract.
The article does not explain an entire purchase contract nor a conveyance (Auflassung) as validly conditional. Various declarations in land transactions have their own requirements. It therefore does not recommend a private additional note alongside the notarial arrangement.
An invented seemingly high price
A seller hears of a high total sum. On enquiry it turns out that a substantial part is to be paid only upon a certain later project decision. But he needs a sufficient available amount for his own plans already beforehand.
He does not enter the possible additional payment as securely available money. Instead, he has the entire proposal examined, including levers of influence, the information pathway and security. The example does not state an appropriate division or a probability of success.
Also ask the event question in the case of a different development
What is to happen in the event of changed planning, a resale or an examination that is no longer pursued? Such situations are matters for contractual advice. The seller should understand whether he is merely waiting for an uncertain event or whether specific verifiable obligations and information are envisaged.
Not every theoretical variant needs to become its own complicated clause. What is important is that the dependencies material to the actual transaction are recognised and appropriately designed. A blanket promise to “pay fairly afterwards” does not replace clarification.
Compare with a complete alternative
Set alongside it a concretely described offer without the same later dependency, if one is available. A freely invented alternative price is not a confirmed counter-offer. Compare your own cash needs, time commitment, possible additional performance and remaining uncertainty.
Tax treatment and costs of such a model also require separate classification. The article does not take a blanket approach to taxation based on a self-chosen payment sequence.
The decision should also remain understandable if the additional payment does not occur. Then you assess the actual conditional transaction and not merely the highest figure with which it was presented in the first conversation.