Garage on boundary exceeding 3 meters by ground filling

So I actually have to orient myself 3 meters from the street and not from the neighbor? My hope was still that the neighbor might also fill in. Who measures something like that later? The land registry office only measures the widths and lengths, right?

Attached is the picture of the affected corner. It is difficult to see the heights. I am photographing from the street (held 20cm higher). We are filling up 80cm opposite the street (including the base plate). The neighboring property is where everything is overgrown.

So I actually have to orient myself 3 meters from the street and not from the neighbor? My hope was that the neighbor might also fill in. Who measures something like that later? The land registry office only measures the widths and lengths, right?

No, either heights are specified in the development plan, then those apply, or the natural terrain applies, that is, before your fill. The street itself is initially irrelevant. The natural boundary line between you and your neighbor +3m applies.

At the street, it is therefore still 60cm higher than the street.

I still haven't really understood how the existing terrain slopes and how you want to change it.
How do you drive onto your property and into your garage if you create a height difference of 60cm at the street? Even a ramp would be too steep (60cm/300cm=20%).
Does the property slope up or down by 1.10m as viewed from the street?
A site plan with house, garage and existing and planned heights of the property, the street and the neighboring property would be helpful.

Otherwise, §5 Lower Saxony Building Code applies
(9) 1 The height of the terrain surface relevant according to paragraphs 1 to 8 and §§ 6 and 7 is that of the natural terrain surface. 2 A change to this terrain surface by excavation is to be taken into account, a change by filling only if the terrain surface is thereby adjusted to the existing or approved terrain surface of the neighboring property. 3 The building supervisory authority determines the height of the terrain surface, as far as this is necessary. 4 In doing so, it may take into account, with consideration of neighboring interests, the connection to traffic areas and sewage disposal systems as well as embankments justified by the existing terrain slope.

If you are lucky or can justify it well, your building supervisory authority will set a favorable terrain surface for you (however, I cannot see any reason here).

should usually not be a problem to get exempted from that. It is actually standard for such issues. Go to the building authority and discuss it there, if necessary also clarify with neighbors.

Then you have certainty!

How the street? But you mean the boundary to the street?

Is that a neighbor boundary? We had the same issue in the development area, it was rejected by the building authority. The reference point was the original terrain.

In our case, the development plan states that the height of the garage is measured from the street from which the access is made and then basically the street to the end, the height of the wall that borders the neighboring property. We were 12 cm over and obtained a permit to deviate from this with the justification that we did not want a slope downwards from the street to the garage, to prevent water from running in.