Isolated garage liberation costs

Hello and good evening :-)
I have a detached single-family house, to which I would like to add a garage (prefabricated garage).
This is slightly outside the development plan for the garage and would have a flat roof instead of the prescribed pitched roof.
The municipality sent me a form to apply for an isolated exemption.
What does such an exemption cost? Of course, this varies from municipality to municipality. On the internet, I find the following information:
“The fees amount to 10% of the benefit you expect to gain from the exemption, but at least 75 EUR.”
What is meant here by benefit? If the garage costs 30,000€, 10% of that would be 3,000€, making the approval more expensive than that of the house?
Thanks for the clarification,
Florian

Why don’t you just ask your [Gemeinde]?

So ours cost about €75.

Also unsere hat so ca 75€ gekostet.

That sounds good. And that was also an exempted permit with insulation, not a normal building application? Of course, I will ask the municipality directly on Monday, but otherwise that stresses me out :)

Thank you!

We built in the exemption procedure and needed an insulated exemption for the garage.

May I still ask what you deviated from the plan?
Asking only to assess the chances of success