Is it permissible to own or benefit from an apartment that was nationalized and then transferred to private ownership by the state? Is it permissible to rent it out or keep it, or must it be returned to its original owner?

What socialist regimes did by confiscating and nationalizing people's property is considered unlawful usurpation (ghasb), and the subsequent transfer of ownership of these properties to others is not valid. Therefore, apartments and real estate still belong to their original owners or their heirs.

If the owners accept compensation, then it is permissible to utilize and own these properties. However, if they do not accept, the property must be returned to them, and they have the right to demand rent from the occupant for the duration of their stay.

The questioner should refer to the government to review the compensation procedures and whether it was fair and accepted by the owners.