The dispute: It is disputed amongst the Rishonim and Poskim as to whether one is to put on Tefillin on Chol Hamoed. Some Poskim rule that Chol Hamoed is not a time of Tefillin [similar to Shabbos and Yom Tov, and it is hence forbidden to wear Tefillin on Chol Hamoed]. [Likewise, according to Kabala, it is forbidden to wear Tefillin during Chol Hamoed.] Other Poskim however rule one is obligated to wear Tefillin on Chol Hamoed. Other Poskim rule [it is questionable as to whether one is obligated to wear Tefillin on Chol Hamoed and therefore] one is to wear the Tefillin without a blessing.
The final ruling: Practically, the Ashkenazi custom throughout all these provinces is to wear the Tefillin on Chol Hamoed and to say a blessing over them, although in Shul the blessing is said in silent. Nevertheless, those that wear it without a blessing are doing a [more] proper custom. [This is the Ashkenazi custom that is followed by many until today. However some Ashkenazim today are accustomed not to wear Tefillin during Chol Hamoed. The Sefaradi and general Chassidic custom is not to put on Tefillin at all during Chol Hamoed. This is likewise the Chabad custom. In Eretz Yisrael the widespread custom amongst all communities, including Ashkenaz, is not to wear Tefillin during Chol Hamoed.]Â Â
The Chabad, Chassidic, Sefaradi, custom is not to put on Tefillin at all during Chol Hamoed. Some Ashkenazim are accutsoemd to wear Tefillin during Chol Hamoed while others are not.
If one was accustomed to wear Tefillin on Chol Hameod may he go back on his custom and stop wearing them?
Yes. This applies even if he has a family tradition tow ear them. Nevertheless he is to perform Hataras Nedarim.
If one was accustomed not to wear Tefillin on Chol Hameod may he go back on his custom and start wearing them?
Some Poskim rule it is forbidden to do so even if one does Hatars Nedarim.
What is one to do if he accidently wore Tefillin during Chol Hamoed?
A Bochur once told the Rebbe he wears Tefillin during Chol Hamoed, as rules Admur in his Shulchan Aruch. The Rebbe stated that he needs atonement for doing so and he went on to prescribe him an atonement.Â
May a single Shul [Minyan] that does not have a set Minhag have some people that wear Tefillin and some that do not?
Some Poskim rule that in the same Shul one may not have some people wearing Tefillin for Davening and other people not wearing Tefillin. Other Poskim rule that it is permitted to have some people wear Tefillin and others not wear Tefillin during the same Minyan, and so was accustomed in various communities.
May one who is accustomed to wear Tefillin during Chol Hameod do so in a congregation that everyone is accustomed not to wear Tefillin?
May one who is accustomed not to wear Tefillin during Chol Hameod Daven Shacharis with a congregation that is accustomed to wear Tefillin?
Some Poskim rule he is to wear the Tefillin without a blessing nd with a Tnaiy.
Is one who is accustomed to wear Tefillin on Chol Hamoed to continue to do so if he moves to Eretz Yisrael?
No. He is to accept the Minhag of Eretz Yisrael and stop wearing Tefillin on Chol Hamoed. If he deesires to nevertheless continue his custom, he is tow ear it in private in his home and without a blessing.
 31/2; Ketzos Hashulchan 7/1
 First opinion in Admur ibid; Michaber 31/2; Raavad in Tamim Deim 40; Bahag brought in Tosafus Eiruvin 96a; Haittur Tefillin 6; Rashba 1/690; Ritva Moed Katan 18b in name of Riy; Rashbi Zohar Chadash 8b; Arizal brought in Kaf Hachaim 31/6; Rameh 108; Grâ€a 31/4 and Maaseh Rav 174; Avnei Nezer 2
 Michaber ibid
 The reason: As the â€œsignâ€ which is the cause for not donning Tefillin on Shabbos and Yom Tov is the particular Mitzvos of that Holiday, such as not eating Chametz on Pesach and sitting in the Sukkah during Sukkos, and these Mitzvos are applicable also during Chol Hamoed. Thus, just as Shabbos and Yom Tov is not a time for Tefillin due to these â€œsignsâ€ so too Chol Hamoed is not a time for Tefillin due to these signs. [Admur ibid; Ritva ibid; Mâ€A 31/3; Taz 31/1]
 Arizal in Shaar Hakavanos Derush 2; Peri Eitz Chaim 5, brought in Kaf Hachaim 31/6; See Mishmeres Shalom 33/8; Beis Rebbe p. 32
 2nd opinion in Admur ibid; Rama 31/2; Rosh Tefillin 16; Tosafus Eiruvin 96a; Tosafus Menachos 36b; Tosafus Chagiga 18a; Ritva Moed Katan 18b in name of Rabbeinu Yehuda and Rabbeinu Shimshon Meshantz; Teshuvos Ashri 28/3
 The reason: As the â€œsignâ€ on Shabbos and Yom Tov which is the cause for one not donning Tefillin is the fact that one must rest from Melacha, and since it is Biblically permitted to work on Chol Hamoed it thus lacks the sign and is obligated in Tefillin. [Admur ibid]
 Semak 150
 Admur ibid; Rama 31/2
The reason: The blessing is not said aloud in Shul as it is said the rest of the year in order to show that Chol Hamoed does contain some holiness of the â€œsignâ€. [Admur ibid; Levush 31] In addition, there are Poskim [Semak ibid] who rule that one is not to say a blessing over Tefillin during Chol Hamoed [even if you desire to wear them]. [Admur ibid; Lechem Chamudos Tefillin 75] Therefore those that are accustomed to recite a blessing are accustomed to do so inconspicuously in order so it does not lead to dispute. This is the reason of our custom of Ashkenaz. [Admur ibid]
Why doing so does not involve Baal Tosef or belittling of the â€œsignâ€ even according to the stringent opinion: Even according to the opinions who rule Chol Hamoed is not a time for Tefillin, those who don Tefillin [in order to suspect for the opinion who obligates it], are not considered to be transgressing the law of â€œBaal Tosif/do not addâ€ or to be belittling the â€œsignâ€ of Chol Hamoed. The reason for this is because they are not intending to do so for for the sake of a definite Mitzvah, but rather out of doubt that perhaps it is a Mitzvah, and it is only considered Baal Tosif when done for certain for the sake of a Mitzvah. It is due to this reason that guarding the second day of Yom Tov in the Diaspora is not considered Baal Tosif. Likewise, due to this reason, certainly there is no need to suspect for the prohibition of belittling the â€œOs/signâ€ of Chol Hamoed, as this prohibition as well onl;y applies when it is done for the sake of a definite Mitzvah. [Admur ibid; Semak ibid; Taz ibid; Mâ€A 31/2 see also Siddur Admur regarding night Tzitzis and 34/4 regaridng Rabbeinu Tam] Based on this it seems that donning the Tefillin is the proper way to act as there is nothing to lose by putting on the Tefillin even according to the opinion who forbids it as explained in the footnote above. However it seems that it is a Mitzvah to publicize to those who do put them on that they may not do so for certain for the Mitzvah but rather only out of doubt. Vetzaruch Iyun if they are in truth intending to wear it out of sdoubt how they can say a blessing over the Tefillin. Perhaps then, this statement of Admur is only going on those who wear it without a blessing, while those who recite a blessing they in truth transgress Baal Tosif according to the stringent opinion.
 Admur ibid; Taz 31/2; Ashel Avraham Butchach 31 â€œThey are nevertheless to say the blessing in their mindsâ€
The reason: As â€œSafek Brachos Lehakelâ€, and the blessings do not invalidate the Mitzvah. [Admur ibif]
 Custom of German and Hungarian communities; Minhagei Chasam Sofer 8/7; Rav Aiva Eiger in Igros Sofrim 47;Â Divrei Chaim of Tzanz directed the Bochurim to wear it, brought in Os Chaim Veshalom 31/1 [see also Minchas Elazar 5/6]; Ashel Avraham Butchach 31
Wearing Rabbeinu Tam: Some Poskim rule that even accoridng to the Ashkenazi ruling and custom one is not to wear Rabbeinu Tam. [Mâ€B 31/8 in name of Pâ€M; Ashel Avraham Butchach 31] Otehrs rule it is to be worn. [Zekan Ahron 2/4; See Shoel Umeishiv 1/247; Piskeiy teshuvos 31 footnote 7]
 Aruch Hashulchan 31/4; This follows the ruling of the Grâ€a 31/4 and Maaseh Rav 174
Why donâ€™t all people wear Tefillin Al Tnaiy? Although above Admur ibid explained that by wearing the Tefillin due to doubt there is no worry of belittling the Os of Yom Tov, and hence seemingly there is no reason to be stringent against wearing the Tefillin during Chol Hameod, Al Tnaiy, nevertheless the custom of all Chassidim, Sefarim and many Ashkenazim is not to do so. The reason for this is because perhaps evern wearing the Tefillin Al Tnaiy contains some belittlement of Cho Hameod and is hence not to be done. Likewise, perhaps one will not know of this Tnaiy and will wear it as a definite Mitzah. [Mishmeres Shalom Kudinav 33/8; See Piskeiy Teshuvos 31/2]
 Michaber 31/2; Kaf Hachaim 31/6; Beis Yosef 31: â€œAt first the Sefaradi in Spain wore Tefillin on Chol Hamoed as ruled the Rosh, however when they saw the words of the Zohar they stopped doing soâ€
 See Os Chaim Veshalom 31/2; Imrei Yosher 2/149; See previous footnotes for Chassidic masters who were accustomed to wear Tefillin on Chol Hamoed.
 Beis Rebbe p. 32 â€œThis was one of the initiations of the Alter Rebbe, that Chassidim not wear Tefillin during Chol Hamoed.â€; Ketzos Hashulchan 8 footnote 4; Piskeiy Hasiddur 55; Igros Kodesh 15/259
 Os Chaim Veshalom 31/1; Divrei Yatziv 1/10
 Chesed Levarahm 9; Sdsei Chemed Chol Hamoed 15; Os Chaim Veshalom 31/1; Minchas Elazar 1/11; Halacha Lemoshe in Kitzur SHUâ€A 10; See Beis Yitzchak 2/88; Shoel Umeishiv 1/247; Piskeiy Teshuvos 31/2
 Beis Yisrael 1/143
 See Os Chaim Veshalom 31/1 for a lengthy discussion on this matter
 Mâ€B 31/8 in name of Artzos Hachaim and other Achronim; Sdei Chemed Chol Hamoed 14; Orchos Chaim 31/4; Beis Yitzchak 2/88; Heishiv Moshe 31; Lechem Hapanim in Kitzur SHUâ€A 10/25; Ashel Avraham Butchach 31; Aruch Hashulchan 31/4; Os Chaim Veshalom 31/1
 The reason: This is forbidden due to the prohibition of â€œLo Sisgodedu.â€
 Chayeh Aryeh 9; Mishnas Chassidim in Tefillin Demarei Ala; Maharsham 359; Maharshag 2/12; Parshas Mordechai 4; Minchas Elazar 1/11; Igros Moshe 5/24; Divrei Yatziv 1/10
 The reason: As Lo Sisgodedu only applies if one rules to others the opposite of the custom. [Maharshag ibid] As Lo Sisgodedu does not apply by a Biblical command. [Maharsham ibid]
 The Maharam Shick wore Tefillin in the Shul even though some wore and some did not. [Maharshag ibid] The Arugas Habosem wore Tefillin in the Shul even though some wore and some did not. Toras Yekusiel 19] In Tzans the Bochurim wore Tefillin in Shul. [Divrei Yatziv ibid]
 Igros Moshe ibid; See Ashel Avraham Butchach 66 regaridng if he should Daven with the Minyan
 See Shevet Halevi 6/2; Divrei Yisrael 1/143; Sdei Chemed ibid; Orchos Chaim ibid; Piskeiy Teshuvos 31/3
 Os Chaim Veshalom 31/1; Shevet Halevi 3/11; Halichos Shlomo 4/20; Betzeil Hachochmah 6/15; Piskeiy teshuvos 31/2