This article is an excerpt from our Sefer
3. Special occasions for Onah [intimacy] obligations:
B. Leil Tevila-Night of Mikveh:
Regarding the obligation for a woman to immerse on time and not to delay Mikveh – See Halacha 1B at length. The following Halacha will deal specifically with the husband’s obligation to be intimate with his wife on the night that she immersed.
Every man is obligated to have relations with his wife on her night of Mikveh [and if he does not do so, it is a matter of danger of having a Dibbuk attach to her soul]. [This applies even if he already fulfilled his minimum amount of Onah, such as if he is a sailor and is only required to do so once every six months. In addition to this intimacy one is obligated to fulfill his minimum frequency of Onah, as stated above in Halacha 2, and it does not come to subtract from it. See Q&A regarding if Mechila of the wife helps on Mikveh night!]
What to do if she went to Mikveh although they are unable to have relations: If, for whatever reason, the couple cannot have relations that night [i.e. too tired or sick, or baby screaming, etc], then she is to sleep with a baby [on her bed, or at the very least in her room], or sleep with a knife under her pillow [or mattress]. Alternatively, women are accustomed to place a garment belonging to their husbands over them to avoid the danger. Some suggest that the above only applies if the husband does not show her any intimacy, however, if he shows her intimacy of hugging and kissing, then the danger is no longer applicable even if they do not have actual intercourse.
Night of Yom Tov: One is obligated to have intimacy with his wife on the night of Mikveh even if it occurs on a Yom Tov, such as the night of Rosh Hashanah, Sukkos, Hoshana Raba, Shavuos, Pesach (including the night of the Seder), with exception to the nights of Tishe B’Av and Yom Kippur, in which case the immersion is to be delayed.
Mikveh night coincides with Yom Chashash: In the event that one’s night of Mikveh coincides with a day of Chashash Veses, then it is forbidden for them to have relations on that night. In such a case, the wife is to push off her immersion in the Mikveh until the next night. [However, in a time of need, such as if her Mikveh night fell on Thursday night which is a Chashash Veses, then she may go to Mikveh that night and not have relations and sleep with a baby, or knife under the pillow or with her husband’s clothing, as stated below in the Q&A. In such a case, the couple is not to engage in hugging and kissing until after the Yom Chashash, due to worry of Zera Levatala.]
May the couple delay Mikveh, or avoid intimacy, if the wife is Mochel [agrees]?
If the husband has already fulfilled the Mitzvah of Peru Urevu, then it is permitted to delay Mikveh if both, husband and wife, consent to it. [In the event that she already went to Mikveh, then the above-mentioned matters must be done if the couple consent to delay intimacy.] If he has yet to fulfill the Mitzvah of Peru Urevu, then it is forbidden to delay even if they both consent. See Halacha 1B in Q&A for the full details on this subject!
Should a woman immerse in a Mikveh if her husband is out of town, or knows that her husband will be unable to be intimate with her due to some other reason?
In the event that the husband is out of town [or the wife knows that her husband will not be intimate with her that night], then she is not to immerse in a Mikveh until her husband returns home and is able to have intimacy with her. This is due to a worry of danger, as an evil Dibbuk can enter her in such a case if she immerses despite the foreseen lack of intimacy, as has occurred already in the past. If she did immerse, then she is to sleep with a baby, or sleep with a knife under her pillow or mattress. [Alternatively, she may place a garment of her husband over her. Likewise, in a time of need, such as her husband will arrive the next day from the Diaspora and she desires to be pure when he arrives, then she may immerse the night before and do as above.]
Not to walk home alone after Mikveh:
It is dangerous for a woman to walk home alone after immersing in a Mikveh.
Not to meet an animal or ignoramus after Mikveh:
A woman who met a dog after immersion and was then intimate with her husband will have children who are ugly. If she met a donkey the children will be dumb. If she met an ignoramus, the children will likewise be ignoramuses. If she met a horse it is beneficial for the children.
 Michaber O.C. 240:1; E.H. 76:4; Tur 240:1 and E.H. 25:2; Admur 613:20 regarding Peru Urevu; Rav Hamnuna Brachos 24a; Beir Heiytiv 240:4; M”B 240:8; Tzava’as Rebbe Yehuda Hachassid (36) 41 “One is not to push off being with his wife on her night of Mikveh”; Kitzur SHU”A 150:8; Kaf Hachaim 240:13; Reishis Chachmah Sha’ar Gimel Chupas Eliyahu in name of Chazal, that so instructed Rebbe Yehoshua to his son; See Piskeiy Teshuvos 240:5
Regarding the general obligation of the wife to immerse in a Mikveh on time: See Michaber Y.D. 197:2; Admur 613:20 that it is forbidden to delay Mikveh due to Bittul Peru Urevu; Y.D. 187:8 that it is forbidden for a woman to delay her Tuma even if her husband is not in the city; All Poskim brought in Halacha 2 regarding a woman not delaying Mikveh; Toras Chaim 240:3, brought in Taharas Habayis 1:105
 Implication of Tzava’as Rebbe Yehuda Hachassid ibid; Zera Emes Y.D. 151 in name of Zohar; Yifei Laleiv 240:3; Kinas Sofrim in Hashmatos of Shiyurei Taharah 64; Minchas Yitzchak 6:249; See Piskeiy Teshuvos ibid
 Shvus Yaakov Y.D. 3:78; Kaf Hachaim 240:14
 Implication of Michaber ibid; Beir Heiytiv 240:4; Ma’amar Mordechai 240:1; M”B 240:8; M”A 240:1 regarding if the wife is asking for his attention; Kaf Hachaim 240:20
 Possible understanding of Michaber and all Poskim ibid; Suggestion in Ashel Avraham Butchach Tinyana 240:2; Taharas Yisrael 2 240:1-12; Meiy Hada’as Inyanim Shonim 12 p. 55; See Sheyikadesh Atzmo 1:1 footnote 1
 Shiureiy Shevet Halevi 197:1
 Piskeiy Teshuvos ibid
 Shvus Yaakov Y.D. 3 :78; Ruach Chaim 240:1; Kaf Hachaim 240:14;
 Ruach Chaim 240:1; Kaf Hachaim 240:13-14
 Mur Ohalos 28; Piskeiy Teshuvos ibid
 Admur 494:3 regarding Shavuos; M”A 240:3; Chesed L’alafim 240:3; Siddur Ya’avetz; Chayeh Adam 130:22; M”B 240:7; Kaf Hachaim 240:5; Chayeh Adam 139:7; Torah L’shma 142; Piskeiy Teshuvos 240:9
 M”A 581:16; Sha’ar Hakavanos p. 90; M”B 581:26; based on Seder Hayom; Sh’lah p. 213 brought in Kaf Hachaim 581:86; Kaf Hachaim 240:5
 Admur 494:3; M”A 494 in name of Arizal ibid; M”B ibid
 See Tahara Kahalacha 24:109
 This can occur in a case that shortly after Mikveh the woman became impure with blood that is not considered period blood [such as a Kesem, or medical checkup, or Besulim blood] and her Mikveh night fell on the night of her Veses. However, if she saw blood of her period, or did a Bedika with blood, then since these sightings require calculation of Chashshos, it recalculates her previous Chashashos of Haflagah and Beinonis in a way that the Mikveh night cannot coincide with them. [See Rama 189:13; Tahara Kahalacha 24:31 and footnote 179, based on Bach; Sidrei Taharah 189:13; Rav Akiva Eiger; Tzemach Tzedek Milu’im 44; See Biurim of Rav Farkash p. 774] However, regarding the Veses Hachodesh, although it is recalculated, she still suspects for her original Hachodesh date from her previous marking. [Rama 189:13] Thus, if she received her period exactly 12 days prior to her Veses Hachodesh, then her Mikveh night can fall on the Veses Hachodesh, which is on the night of the 13th day after her period.
 Kreisy Upleisy; Sidrei Taharah 184:14; Chavas Da’as Biurim 184:13; Sheilas Ya’avetz 2:10; Givat Shaul 62; Noda Beyehuda Tinyana Y.D. 117 [even by a Kallah]; Chasam Sofer Y.D. 170; Even Shoham 14; Pischeiy Teshuvah 184:22; Lechem Vesimla 192:29; Pardes Rimonim 192:27; Ben Ish Chaiy Tzav 2:6; Shevet Halevi 2:112; Koveitz Zalman Shimon p. 142; See Taharah Kahalacha 10:25
Other opinions: Some Poskim rule that if she is immersing for a Rabbinical impurity, then she may immerse that night and have relations. [K’neses Yechezkal 33, brought in Beir Heiytiv 184:14, brought and negated in Pischeiy Teshuvah 184:22; Shoel Umeishiv Kama 1:7; Chochmas Betzalel p. 698] Regarding a Kallah and Beilas Mitzvah, some Poskim are lenient to permit it. [Darkei Teshuvah 192:45 and 47 in name of Shem Aryeh and Sefer Hamakneh in Kuntrus Achron; Koveitz Zalman Shimon p. 142 regarding Onah Bienonis] Many Poskim, however, argue on this and prohibit even by a Kallah and Beilas Mitzvah. [See Poskim above and Tahara Kahalacha ibid footnote 45]
 Aruch Hashulchan; Taharas Yisrael; Darkei Teshuvah; Maharam Shick 364; Nitei Gavriel Niddah vol. 2 102:2; So ruled to me Rav Farkash in a phone conversation and so he rules in Tahara Kahalacha ibid and footnote 177; See also See Poseiach Sha’ar 23:27; Beir Moshe 8:91; Piskeiy Teshuvos 240 footnote 44; See Sheyikadesh Atzmo 11 footnote 4; Shut 38 in back of Sefer
The reason: As this can lead to them having intercourse. [Poskim ibid; however, see Tahara Kahalacha ibid footnote 177 who negates this reason] Alternatively, it is because it is a danger for her to immerse and not have relations, as stated in the above Q&A. [Tahara Kahalacha ibid]
Other opinions: Some Poskim rule that in such a case of a Chashash Veses on the night of Mikeh, she should immerse that night and the couple should have relations during daytime. [Or Tzadikim 32:4] Some Poskim rule that she may go to Mikveh that night and the couple may hug and kiss, and then have relations the next day after the Veses concludes. [Even Shoham 14, brought in Pischeiy Teshuvah 184:22; Sheilas Ya’avetz ibid; See Rama 184:10 and Admur 184:33-35; Chut Shani Niddah 197:3; Shevet Halevi 8:271]
 Tahara Kahalacha 21:10 in name of Vayan Yosef 29; If, however, she did not do so, she may Tovel on Friday night.
 Even Shoham 14, brought in Pischeiy Teshuvah 184:22; Sheilas Ya’avetz ibid; Tahara Kahalacha 24:109 and footnote 177
 See Poseiach Sha’ar 23:27; Piskeiy Teshuvos 240 footnote 44
Other opinions: Some Poskim rule that she may go to Mikveh that night and the couple may hug and kiss, and then have relations the next day after the Veses concludes. [Even Shoham 14, brought in Pischeiy Teshuvah 184:22; See Rama 184:10 and Admur 184:33-35]
 Pesakim Uminhagim of Maharam Merothenberg 161 [May delay if water is cold and husband and wife both agree]]; Tashbeitz Katan 480; Zohar Mishpatim ibid [that the Aveira is only if the husband minds her delay], brought in Beis Yosef Y.D. 197, Olas Tamid ibid and Kaf Hachaim 240:16; Rav Poalim Y.D. 2:34 that they may delay with mutual consent if has another Mitzvah to do that night; Rav Azriel Hildsheimer Y.D. 1:191; Shoel Vinishal 3:422; Mishneh Halachos 12:92; Mayan Omer 7:91; Simchas Yehuda p. 40-43; See Halacha 1B in Q&A for other opinions and the full details on this subject!
 Shvus Yaakov Y.D. 3:78; Kaf Hachaim 240:14; Betzel Hachochma 3:71; Shevet Halevi Y.D. 197:1 that so is the custom amongst majority of Jewry; Piskeiy Teshuvos 240:5; See regarding that is it not a Mitzvah to go to Mikveh if her husband is not in town: Admur 326:7; 613:20; Michaber 197:2; Rama 197:3; Rabbeinu Tam in Tosafos Niddah 36a and Yuma 8a]
Other rulings of Admur and other Poskim: However, see Admur Y.D. 187:8 that it is forbidden for a woman to delay her Tuma even if her husband is not in the city, and so rules Shevet Hamussar 24; Darkei Teshuvah 184:64. [See Likkutei Sichos 14:27 footnote 58 that leaves this in Tzaruch Iyun; See Tahara Kahalacha 21:1; See there Biurim 1 for explanation of Admur ibid however practically, the custom is not to immerse when the husband is not in the city, even during the week. [See Piskeiy Teshuvos 240 footnote 45; Shiureiy Shevet Halevi 197:1; Tahara Kahalacha ibid; Mishneh Halachos 9:179; Minchas Yitzchak 6:149]
 Kaf Hachaim 240:14
 Shiureiy Shevet Halevi 197:1
 Zivcheiy Tzedek Y.D. 116:125; Kaf Hachaim 240:15
 Rokeiach 317; Kaf Hachaim 240:15