402 Checking Correct Placement of Mezuzos
As part of our teshuvah preparations for the new year to ensure that we are fulfilling mitzvos properly, it’s a common custom to have one’s tefillin and mezuzos checked during the month of Elul. In fact, according to some opinions tefillin and mezuzos should be checked every twelve months. Checking mezuzos entails not only ensuring that our mezuzos are kosher, but also that the makom kevi'as hamezuzos (the place where the mezuzos are affixed) is in accordance with halachah. If the mezuzos are not in their proper places it is as if one is not fulfilling the mitzvah at all, chas veshalom. The mezuzah must be affixed to the right doorpost derech bi’aschah (as you enter the doorway). However, there are complex halachos regarding which is considered the right side if two rooms have a shared doorway; in such a case, one should seek the advice of a rav to ensure that the mezuzah is placed in accordance with halachah.