Were you overly cautious or did you even have to provide additional funding?

There are laws for that and they clearly state: private person = prices are gross!

One naively posts their calculation list online and then has to endure a gross-net discussion.... speechless!

One kindly puts their calculation list on the web and then has to endure a gross-net discussion... speechless!

Indeed off-topic. But that has nothing to do with your list. Of course, you can put gross-net in there if you enjoy it.

We separated from our developer precisely because of the fact (Netto-Brutto Preise). We had the heating engineer at home & I explicitly asked for gross prices, but the offer stated exactly the mentioned price...... in net.... That’s how we do business....

Of course, he couldn’t remember a week later that I only asked for gross prices.

For me an absolute no-go.