By Horav Yosef Yeshaya Braun, member of the Badatz of Crown Heights
Are Mezuzos Required for Property Owned Jointly by a Jew and a Non-Jew?
The halachah is that a residence or business that is co-owned by a Jew and a non-Jew requires mezuzos—but they should be affixed without a blessing.
The reason for this ruling is the difference of opinion among poskim whether the mitzvah of mezuzah applies to such a property; in order to comply with both opinions, mezuzos should be affixed, albeit without a blessing.
In a case where there is reason for concern that the non-Jewish owner might remove the mezuzos, then, and only then, should mezuzos not be put up.
In the case of a mixed “marriage” chas veshalom, Rachmana litzlan, regardless of which partner is Jewish, the same halachah applies.
This is because these days it is customary for both the husband and the wife to have legal rights to the home.