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

In my house sale, the house price and items in the house were also listed separately. The notary explicitly pointed out that the real estate transfer tax is only calculated on the house price. I didn’t care either, as it didn’t affect me.

Yes exactly, that’s normal, for movable items sold along with the house, no real estate transfer tax is applied. However, one should not overdo it. For friends of ours, the tax office actually came and, after numerous correspondences, had an expert determine whether what was stated was correct. They had quite a lot of furniture custom-made by a carpenter and precisely tailored to the specific house, which was bought along and correspondingly declared in the purchase contract. All the invoices from the carpenter were also available, yet the tax office sent an expert for verification because the amount apparently seemed too high and therefore “fishy” to them. This expert checked everywhere whether and how the piece of furniture was attached to the building and if it could also be placed elsewhere. Ultimately, he confirmed that everything was in order. Until then, however, our friends were sweating blood and water.

Until then, however, our friends had been sweating blood and water.

They must have calculated out half the house for someone to lose their bodily fluids so intensely.
Real estate transfer tax is annoying but manageable when buying a property. No one has to sweat over that.
Regarding the question:
Brokers receive a percentage of the sale price that is anchored in the notary contract.
This reminds me of my first house purchase; the elderly lady (broker) came along out of courtesy to practically hold my hand. She was a kind of old school: accompanying from start to finish.

Half the house must have been written off for one to lose their bodily fluids so intensely.

... and if you haven't brought enough equity, you have to sweat at the bank a second time, because of course the bank only uses the pure purchase price of the house as the basis for determining the lending value.
Quite often there is cursing and crying because the higher interest rate more than outweighs the saved real estate transfer tax – unless, as mentioned, you have enough equity in the financing.

Half the house must have been written off for someone to lose their bodily fluids so intensely.

No, not that, the provincial tax office was possibly just not used to such sums. The house price was already remarkable, and the inventory made accordingly for every corner was the same. For the furniture, a current value was determined and applied accordingly; for a house not even 2 years old, that was naturally still high. The question was whether the tax office would ultimately assess it the same way as the expert consulted before the purchase or not. If not, it would have ended up being a substantial amount including the penalty. Hence the unrest... But in the end, everything was correct (first of all, the tax office examined the original invoices to verify their authenticity, which was a huge circus affecting not just our friends as buyers). As said, everything was lawful.

I just wanted to say that movable inventory can be separately listed in the purchase contract and no property transfer tax needs to be paid on it, but one should not think they can simply overstate the furniture to save taxes. One should stay within reasonable limits regarding the amount declared.

... and if you haven’t brought enough equity, you have to sweat a second time at the bank, because of course they only take the pure purchase price of the house as the basis for the determination of the loan-to-value ratio. Often enough there is swearing and crying because the higher interest rate more than compensates for the saved property transfer tax - unless, as mentioned, you have enough equity in the financing.

No. It’s about deducted costs: if deducted furniture is only partially accounted for, you should still have that amount available in your checking account. Example: €50,000 withdrawn (kitchen, awning, fixtures), only 50% is accounted for (kitchen, awning), then in NW for example with 6.5% property transfer tax ... calculate, calculate ... €1,625. Anyone who sweats blood and water over that or still has to get another loan has overextended themselves. Period.

.. and if you haven't brought enough equity, you have to sweat a second time at the bank, because of course they only take the pure purchase price of the house as the basis for the mortgage lending value determination.

Raising the capital is not always the problem, nonetheless those who have more than enough feel sorry for it, and a penalty for tax evasion even more so, because it is not done with a fine alone. But the house and the circumstances are not comparable to the average. That was not the point of my description as written above either, but to warn to stay realistic in all tax avoidance, otherwise you might have trouble afterward.