Financing comparison - Now it's getting serious

Well, you will have some specifications on how you can develop the property. For example, the standard land value in our area was based on a floor area ratio of 0.5. If we were allowed to build a high-rise on the property, the standardized land value would be adjusted upwards using conversion coefficients (available from the appraisal committee). If the floor area ratio of 0.5 is not achievable, the same adjustment is made downwards. The approach of the MBS is of course in your favor… With a remaining debt of €37,000 and 18 months of fixed interest remaining, I would have ING calculate the prepayment penalty for a voluntary repayment, or was that refused by the bank? If ING shows willingness to cooperate, factor in the costs and present the project as a virtually unencumbered property or at least with a first-ranking mortgage on the property that you bought below market value due to good relationships (unless it was municipal land back then)… this should increase the number of possible financing banks

At the risk of repeating what has already been said, large plots are almost always devalued.
What was the reason again why you got it so cheaply?

According to Boris, however, the BUILDING LAND is worth 100 €/sqm.

And since we are converting the entire plot, why shouldn't the whole plot be entirely worth that.

The standard land value at that time, Dec. 2017, was €40 / sqm. Currently €100 / sqm.

ING does not do that. I am considering whether to make the MBS financing for 10 years. By then, a lot will be paid off and the land value is likely to rise enormously, since it currently does not even remotely reflect the applicable price here.