Property acquisition tax on house construction - when?

A note from a neighboring thread ( ):

I just discovered a document from the Federal Ministry of Finance that appears to be a kind of guide for the assessment of real estate transfer tax and lists quite a few different constellations and how these are to be evaluated in terms of real estate transfer tax. Just google "grunderwerbsteuer bundesfinanzministerium 2017" (PDF document) for this, in case this document is not already known here in the forum...

I have seen that - it is very informative. According to that, our ‘Geschichte’ is definitely a linked transaction. Let's see when the FA gets in touch ;)

Today, mail arrived from the tax office, but only a "standard value notice - reassessment as of 1.1.2021," because at the tax office our property is still registered as undeveloped. At the same time, there was a "property tax assessment notice - reassessment as of 1.1.2021," which stated that this serves as the basis for calculating property tax. The property tax will then be sent separately in a property tax notice from the municipality. From when is the property considered developed?

I suppose from the day you notify that the construction is completed, or possibly from the 1st of the month in which that happens - or else from the following month.