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Affixing Mezuzot before Thirty Days in a Rental Dwelling
My husband and I are both doctors. We just signed a contract for a rental apartment close to the hospitals that we will be working in. I was told that I didn’t have to put up mezuzot until the night of the thirty-first day that we are living there. But, I’m afraid that with our hectic schedules we will forget. Is it allowed to put them up from the beginning if we want to? Can we make a berachah?
A: The Gemara states that when one rents a dwelling (outside of Israel), he only becomes obligated after thirty days.
Rashi explains that until thirty days have elapsed, one can easily change his mind about the rental; thus, the house is not really “his” until thirty days are over. Tosafot explain that the first thirty days of residence are considered as “temporary dwelling,” and temporary dwelling does not obligate one to affix a mezuzah.
Based on Rashi’s explanation, it follows that when a long-term contract is signed which legally obligates the renter for an extended period, the obligation of mezuzah would take effect immediately. Moreover, if upon moving into the house, the renter improves the dwelling in a manner which shows that he is planning to remain there for a long while, logic dictates that a mezuzah should be put up and the proper blessing recited.
Consequently, the custom has developed to put up mezuzot immediately. Some authorities allow a berachah to be recited at that time. One can rely on this view.
However, some poskim advise that though the mezuzah should be affixed immediately upon moving in, the blessing should not be recited until the thirty-day period is up. R. Moshe Feinstein rules that the mezuzah need not be removed and replaced at that time. One may merely place his hand on the mezuzah and recite the blessing.
There are authorities that opine that it is proper at that time to remove just one mezuzah, recite the blessing, and return the mezuzah to its proper place. If the thirty-day period concludes on Shabbat or Yom Tov, the mezuzah should be affixed on Friday, erev Shabbos or on erev Yom Tov before lighting candles. The blessing can be recited at that time.
 Menachos 44a.
 Chayei Adam 15:22; Aruch HaShulchan 286:49, cited in R. Doniel Neustadt, The Mitzvah of Mezuzah, Torah.org (https://tinyurl.com/p7jevhg); Agur B’ohalecha cites Igros Moshe Y.D. 1:179, Minchas Yitzchak 10:93, and Mezuzot Beitecha 286:76.
 Igros Moshe Y.D. 1:179.
 The Mitzvah of Mezuzah, Torah.org (https://tinyurl.com/p7jevhg); See, however, Agur B’ohalecha 7:5, citing Shach 286:25; Aruch HaShulchan 286:24; Sha’arei HaMezuzah, citing oral ruling of Shevet HaLevi.