When to Wear Tefillin
This is the approved revision of this page, as well as being the most recent.
Shabbat and Yom Tov
- Tefillin are not worn on Shabbat and the major holidays including Pesach, Shavuot, Rosh Hashana, Yom Kippur and Sukkot. The reason given are, that these holidays are themselves "signs" which render the use of Tefillin, which are to serve as "signs" themselves, superfluous. 
- The Tefillin are removed before we recite Mussaf on Rosh Chodesh. 
- There are several different opinions as to the exact proper time to remove one's Tefillin before Mussaf. Some say that one should take off one's Tefillin after the Kaddish which is recited before the Shemona Esreh of Mussaf, after "uva litzion".  According to a number of authorities the Tefillin should be removed while reciting "uva letzion", just before beginning the "yehi ratzon" paragraph.  Some recommend before Torah reading.  Some recommend after returning the Torah to the aron.  Some say that this depends on how you will be able to wrap your Tefillin (see footnote) 
- One who forgot to remove his Tefillin before Mussaf and realized this while in middle of Shemona Esreh does not have to remove his Tefillin at that time 
- In the event that one forgot Yaale Viyavo in Shacharit but only realized after one removed one's Tefillin, one should preferably put one's Tefillin back on and pray Shacharit again. If it is too difficult, one may be lenient since one has already fulfilled one's obligation. 
- In the morning, one should wear one's Tefillin during the Megilla reading even if one has already worn them. 
See the full in depth discussion about Tefillin on Chol HaMoed here.
- The minhag of some Ashkenazim is to wear Tefillin on Chol HaMoed, however, the minhag in Israel and minhag of Sephardim is not to wear Tefillin on Chol HaMoed. Someone who doesn’t have a minhag should not wear Tefillin on Chol haMoed. 
- One who wears Tefillin should stipulate before wearing the Tefillin that if there’s an obligation then I wish to fulfill that obligation, and if not, I have no intention of fulfilling the mitzvah with my action. 
- If one wears Tefillin on Chol HaMoed one shouldn’t wear Tefillin of Rabbenu Tam (even if one usually wears Tefillin of Rabbenu Tam). 
- Some authorities hold that if some people in the Shul wear Tefillin and others don’t there’s a violation of Lo Titgodidu (don’t cause factions in observance of Torah) and so they advise that one should either find a shul that has your minhag or pray in different locations in the same shul. 
- Mishna Brurah 131:7, cf Biur Halacha 37 s.v. BeShaat
- Shulchan Aruch 31:1, Mishna Brurah 31:1, Kitzur Shulchan Aruch of Rav Rephael Baruch Toledano, siman 10, laws of tefillin on shabbat and yom tov, seif 1
- Shulchan Aruch 25:13, Shulchan Aruch 423:4, Mishna Brurah 25:59, Kitzur Shulchan Aruch 10:19, Rivevot Ephraim 7:317, Kaf Hachayim 25:94, Mishna Brura 25:59.
- Beit Yosef 25 s.v. "ubayom" writes that since in Kedusha we recite that the angels should give Hashem a crown it would be improper for us to show our crowns, the Tefillin. This is quoted in Mishna Brurah 25:61, Magen Avraham 25:32, Taz 25:16, Pri Megadim Mishbetzot Zahav 25:15 as well as Shulchan Aruch Harav 25:41. Levush 25:13 writes that even those whose Nusach does not say "Keter" and instead is "Naaritzcha", should remove their Tefillin for Mussaf.
- Levush 25:13 and Mishna Brura 423:10 write that the reason Tefillin are removed before Mussaf is in order to add a Yom Tov flavor to the day (that the Mussaf itself is considered an "אות". As Mussaf represents the Yom Tov nature of Rosh Chodesh the Tefillin are removed at that time.
- See Kaf Hachayim 25:94 for Kabbalistic reasons behind the removal of Tefillin before Mussaf.
- Kitzur Shulchan Aruch of Rav Rephael Baruch Toledano, siman 10, laws of the donning of tefillin, seif 34. Magen Avraham 423:6, Pri Megadim Eishel Avraham 423:6, Machzik Bracha 15, Mishna Brurah 25:59, Kaf Ha’chaim 25:94.
- Mishna Brurah 25:59, Elya Rabba 25:25.
- opinion cited by Magen Avraham 25:30 though he disagrees, Levush 423:4 and Rema Mipano 108 indicate that some authorities recommend removing the Tefillin before the Torah reading as it also represents the Yom Tov nature of the day, others recommend removing the Tefillin before Hallel for the same reason.
- Opinion cited by Magen Avraham 28:30, though he himself disagrees
- Mishna Brurah 28:8 writes that leaving the Tefillin exposed and unwrapped for the duration of Mussaf is unbecoming the reverence owed to them. In fact, according to halacha, whenever one removes Tefillin one is to wrap and put away the shel rosh before even removing the shel yad! There does not seem to be any good reason why this halacha should be ignored on Rosh Chodesh.
- Pri Megadim mishbetzot zahav 34:2, Mishna Brurah 124:17, Igrot Moshe, OC 4:19, Tzitz Eliezer 11:10 say that folding the Tefillin during the repetition of Mussaf is also not an option as one is required to listen attentively to the repetition and not engage in any other activities.
- Kaf Hachaim 28:7 writes that one who has enough time to fold them in between Kaddish and Mussaf should do so. He writes that if one does not have time one should cover them. Rivevot Ephraim 1:281:5 agrees.
- Teshuvot Vihanhagot 1:45 says that if you will have to leave your Tefillin unwrapped during Mussaf it is better to just wrap them up before Kaddish.
- Chesed Laalafim 25:13, Mishna Brurah 25:61, Kaf Hachaim 25:98, Rivevos Ephraim 8:13. See, however, Peninei HaRav (p. 101).
- Sh"t Yechave Daat 6:6. The Chida in Machazik Bracha 25:13 writes that according to Kabbalah one may not put one's Tefillin back on after one recited Mussaf unless one has not yet put on Tefillin that day.
- Mishna Brurah 693:6, Magen Avraham 693:2, Baer Heitev 693:3. This is based on the gemara in Megilla 16b which says that the word "viykar" in Esther 8:16 relates to the Tefillin that after the death of Haman the Jews continued to put on Tefillin. Moed Likol Chai 31:88 says that one the word "viykar" is read one should kiss one's Tefillin.
- Shulchan Aruch 551:1
- Shulchan Aruch and Rama 31:2, Sh”t Yabia Omer 3:5(3), Ben Ish Chai Parashat Vayera Halacha 12, Kitzur Shulchan Aruch of Rav Rephael Baruch Toledano, siman 10, laws of tefilin on shabbat and yom tov, seif 1.
- Some rishonim forbid tefillin to be laid on Hol HaMoed as they consider the days have the same status as a festival which in itself constitutes a "sign" making the laying of tefillin unnecessary. These Rishonim include: Baal Halachot Gedolot (cited by Tosafot Moed Katan 19a s.v. Rabbi Yosi), Rambam (Hilchot Yom Tov 7:13; explained by Kesef Mishna), Rashba (Sh"t HaRashba 1:690), and Ri (cited by the Hagahot Maimoni Hilchot Tefillin 4:9).
- Other rishonim argue and hold that Chol HaMoed does not constitute a "sign" in which case tefillin must be laid on Hol HaMoed. These Rishonim include: Rambam, Rosh (Hilchot Tefillin 16), Or Zarua 1:589, and Maharam of Rothenburg cited by the Mordechai.
- The Bet Yosef writes that the minhag of Sephardim is not to wear Tefillin on Chol HaMoed based on Kabbalistic sources. This is also the opinion of the Vilna Gaon (Bi'ur ha-Gra Orach Chayim 31:2 s.v. V’yesh Omrim and Maaseh Rav n. 174). Igrot Moshe 4:105:5 writes that the minhag of Israel is not to wear Tefillin.
- The Tur (Siman 31) quotes some rishonim who are uncertain whether one must lay tefillin on Chol HaMoed and concludes that one should wear Tefillin without a Bracha. These opinions include the Ritva (Eruvin 96a), Smag (Eruvin 153), Meiri (Moed Katan 18b), and Taz 31:2. The Mishna Brurah recommends that on Hol Hamoed one make a mental stipulation before donning tefillin: If I am obligated to don tefillin I intend to fulfill my obligation and if I am not obligated to don tefillin, my doing so should not be considered as fulfilling any obligation; and that the blessing not be recited. The Rama writes that the Ashkenazic custom is to wear Tefillin with a Bracha which is to be made in an undertone. See further: Rabbi Jachter on koltorah.org.
- Sh”t Teshuvot VeHanhagot 2:332
- Mishna Brurah 31:8
- Mishna Brurah 31:8
- Kitzur Shulchan Aruch 10:25 writes that there is an issue of Lo titgodedu for some people in the shul to wear Tefillin on chol hamoed and others not to wear Tefillin. Rav Moshe Feinstein in Sh"t Igrot Moshe O"C 4:34 dated Kislev 5737 state clearly that one should follow the minhag of the Shul and if the minhag is to wear Tefillin one should also, and abrogating the minhag of the Shul would be Lo Titgodedu. Hilchot Chol HaMoed Zichron Shlomo (in the hebrew section pg 39-40) prints a copy of this letter. However, Rav Moshe Feinstein in Sh”t Igrot Moshe O”C 5:24 (pg 79 s.v. Al Kol Panim) dated Kislev 5743, writes that in crowded shuls where there’s many who wear Tefillin and many who don’t there’s no issue of Lo Tasu Agudot since it’s clear that there’s two different minhagim. However, Rav Moshe adds that preferably someone who is praying in a shul that wears Tefillin should also wear Tefillin. Sh”t Teshuvot VeHanhagot 2:332 holds that there’s no real issue of Lo Titgodedu but preferably one should be concerned for those who hold that it’s an issue. Rabbi Schachter on yutorah.org (min 36-7) ruled that it is an issue for some people in one minyan to wear Tefillin and others not to wear Tefillin, however, two minyanim in one shul may not be an issue.