Why not a separate address in the same rental house for the upstairs neighbor?

Questioner

I live in a converted house that now has separate apartments upstairs and downstairs. However, it is only 1 address so we share the mailbox and house number. I don't know the lady upstairs and have nothing to do with her, but we live together on paper because it is not a separate address. Is this legal? and if so, what do you need to take into account in connection with tax surcharges because I have heard rumors that you can get into big trouble with this because on paper you live together at 1 address?

Lawyer

Yes, that is completely legal: the house is not split into separate homes, there is no permit for it or will not be issued. So you live together on paper and this can lead to a number of consequences that will cost you. Such as missing out on rent allowance. The tax authorities must know that these are two separate independent homes and you must prove it.