Negotiate design planning costs with architects

Such things are negotiated beforehand. Good work should be well paid. I hardly believe that your draft was submitted just like that. As a layperson, you cannot check and consider everything. Not to mention more detailed plans. Or are you building in the acknowledgment procedure? How does that work without approval planning? The architects are also very busy. With such an action (negotiating afterwards) you "poison" the relationship. How much discount do you want now? As you yourself write, it is about a total of 9,000€. So we are talking about a few hundred euros here or there. It's not worth it. Of course, such sums add up, but with house building, altogether different things will come up for you. Possibly also things that you did not consider despite careful planning. For the further steps, the price can be addressed. Are you using the latest table (2021)? With this one, for 500,000€ of eligible costs, you are already at the lowest level (low requirements) across all service levels at a total of over 80,000€.