I Denmark there are so many difference taxes. The most unfair of them all is "lejeværdi af egen bolig" which directly translates to "Rental value of your own house".

Short version. Had you chosen to rent out your house to someone else instead of living there yourself, you would have made a profit". You have to pay taxes on that value.

"But, hey stop wait a minute", you might say. "I am not renting out my house. I am actually living there all by myself."

Well sorry, that is irrelevant. You still have to pay taxes of that imaginary profit regardless if you live there or not.

The tax rule (in Danish) https://tax.dk/jv/ch/C_H_3_2_2_2_3.htm

WTF? Yes, WTF but true.