How to deal with increasing property tax burden?

It is about the settlement of costs that arise in connection with a property.

Then you have to abolish the property tax. The municipality does not incur any costs due to the property. At most due to the house – but those are costs that are already paid within the framework of water, sewage, etc. anyway.

First of all, it must be said that taxes are not earmarked, otherwise they would be fees. In this respect, it is not about genuine cost recovery. Besides revenue for the municipality (which does not have many possibilities to generate such), it is also about a steering function in terms of social justice. But precisely from this background, I agree with your demand that the building does not belong in there. Because the aim is to promote buildings that use living space efficiently on the scarce resource of building land. So the same property tax for the plots, but whoever builds an apartment building on it divides it among more households. Those who indulge in the luxury of a single-family house simply have to bear the same tax alone. This logic is undermined by the income approach. I also do not think that is good.

I am rather expecting a point catalog that comprehensibly calculates the value of the property.

You can find the determination of the standard value on the internet and by request at your tax office.

It is about settling the costs that arise in connection with a property.

No, that is exactly not the case. Taxes are never earmarked but are sources of revenue from which a budget is financed. In this case, the municipal budget of the municipality in which the taxed property is located.

Otherwise, I find it perfectly okay to use a kind of local social tax. The costs for all kinds of voluntary services (library, school buses, ...) are transparently presented there. Then the share per resident over 18 is determined.

If taxes were earmarked, there would be no way for budgets to respond to local or suddenly emerging situations. Earmarked revenues are contributions such as those for pension insurance or social insurance social insurance. As for the use of your tax money in your municipality, you can simply look at the municipality's budget. These are public. The resolutions passed by a council are also public, and even most parts of the meetings and minutes are public. More than that: you can get involved, because in most municipalities the decision-makers are citizens like you and me who work on a voluntary basis. And: citizens are not paying customers of any state system but shapers of their democratic society.

Yesterday our new property tax assessment arrived. From 290€ to now 960€

Yesterday we received our new property tax assessment. From €290 to now €960

That’s quite a lot. Is it due to a change in the multiplier rate or a completely different valuation by the tax office?
If it’s the tax office: Some have reported repairs on the house as modernization measures rather than maintenance measures. For modernization, the tax office assumes an increase in value, but not for maintenance. You can still have this "reporting error" corrected.

Seen the notice for a garage plot (not mine). Quadrupling!