Close with a different selling price than discussed with the broker?

It really gets interesting with income-producing properties, such as commercial real estate (from multi-family houses or offices or hotels, etc.). Here, the purchase price = market value can easily be twice as high as the loan value. So with 50% equity, you still have to pay a 100% financing.

Am I missing something? If I have a market value of €450,000 and €225,000 equity capital. Then I only have to finance €225,000. Where is the disadvantage if I pay less property transfer tax on €50,000 because I pay that for furniture and 6 curtains. My loan amount then decreases and thus the interest I have to pay.

There are depreciation rules (AfA) for this.

Then you would have to know the purchase price + installation cost. And it is totally unrealistic if a kitchen is depreciated after 10 years - or has a residual value of 1€. Obviously, it is worth much more. Even if it is 20 years old and well maintained (including electrical appliances - stove, microwave, refrigerator). Certainly something under 10,000€. But 1€ cannot be legal. Taxes must be based on actual facts.

Am I missing something? If I have a market value of €450,000 and equity of €225,000, then I only have to finance €225,000.
Where is the disadvantage if I pay less property transfer tax by €50,000 because I pay that for furniture and 6 curtains? My loan amount is then reduced and therefore the interest I have to pay.

Totally - you are quoting part of my post regarding income-generating properties, which absolutely do not play a role in this particular case.
You are mixing up a lot of things.

Look at my concrete example #13. There I explain that it can be more expensive to save property transfer tax because, in return, I have to pay a higher interest rate on the financing.

Then you would have to know the purchase price + installation cost.

I cannot imagine that an owner or buyer throws away their invoice for the fitted kitchen. If they do, it's their own fault. And with a fitted kitchen, they look at the bottom right because the installation is included. Many things are not as complicated as they are made out to be here. These are common procedures that the notary and the tax office know.

Sorry, I want to correct, but it doesn't work. You, , don't have to make a big deal out of everything and act as if all this is completely new – mind you – for the other professionals like the notary or tax office. If you get advice or information here, then accept it, but don't create a never-ending loop here like the daily groundhog.

The notary did not check anything with us. We still had all the invoices for the kitchen, awning, bathroom furniture, of course, and also told the buyer the individual amounts. He asked the notary if it would be possible to accept amount X for everything in the contract. The notary's answer was, "If you want it that way, I'll include it as such." Whether he would have said the same with a ratio of €330,000 to €20,000, I don't know. The purchase price was significantly higher and the amount for furniture was only slightly higher.