Shabbos Evening
Performing marital relations on Friday evening is considered praiseworthy by chazal and in unison with the spirit of Shabbos1Siddur Beis Yakov, poskim.. In fact, they established this to be an obligatory time for talmidei chochomim and, by way of example, other Jews2Mehaber 240:1. Shulchan Aruch Admur Hazoken 280:1.. This time is considered to be spiritually beneficial to the souls likely to be drawn down.
On Rosh Chodesh it is also considered praiseworthy to perform one’s marital duties3Be’er Hetev 240:3. See Sha’ar Hatzion 240:3..
On the night of the mikveh, one is obligated to perform his marital duties4Mehaber 240:1..
Daytime
Marital relations during the daytime are discouraged strongly5Considered “brazenness,” Even Haezer 25:5. Note reference there in parenthesis to Mehaber 240:11. Note the reason quoted in Mishnah Beruroh 240:44, “lacking in modesty.”. Relations are only permitted under certain conditions, for example when the husband feels he is losing control of his yetzer harah6Mishnah Beruroh 240:46.—and then only when the room is totally darkened7Mehaber 240:11. See Ramo. Darchei Tahara Chapter 22 page 200. Note also Sha’ar Hatzion 240:27, 28..
Forbidden Dates
Yom Kippur. On Yom Kippur, the husband and wife are obligated to behave with one another exactly as they would during her actual time8Shulchan Aruch Admur Hazoken 615:1..
These limitations extend to all areas of activity normally forbidden during niddah 9Shulchan Aruch Admur Hazoken 615:1., there being no difference between the night and day of Yom Kippur10Shulchan Aruch Admur Hazoken 615:1..
These limitations begin briefly prior to bein hashmoshos11Sugah Beshoshonim 38:18. on erev Yom Kippur12Be’er Eliyahu, 38:18 note that this is referring to briefly before ben hashmoshos. See Mehaber and Mishnah Beruroh 608:1 and Shulchan Aruch Admur Hazoken 608:3 for details defining this time. See, Mehaber and Shulchan Aruch Admur Hazoken 624:2..
They finish after the tosefos Yom Tov, even before havdala is made13Sugah Beshoshonim 38:19. See Be’er Eliyahu 38:19..
Prior to Yom Kippur it is permissible for the husband to swing the chicken used to perform kapparot around his niddah wife’s head14Sugah Beshoshonim 38:1. If there exists some difficulty in her doing so, they should, however, exercise caution not to touch one another.. Likewise, the niddah wife is permitted to swing the chicken around the husband’s head15Sugah Beshoshonim 38:1..
Tisha BeAv16See Mehaber 554:1.. It is forbidden to touch one’s wife during the evening of Tisha BeAv, even though she is not niddah17Mishnah Beruroh 554:37.. It is also recommended to refrain from passing objects one to the other, as well as all the other limitations normally kept during niddah18Sugah Beshoshonim 39:2. In places where the women dress up it is suggested that they refrain from touching even during the daytime, Sugah Beshoshonim 39:3. See Mishnah Beruroh 554:37..
Most poskim hold that the above limitations do not exist during the daytime19Magen Avrahom 554:19. Mishnah Beruroh 544:37. The reason for any leniencies regarding Tisha BeAv during the day (in juxtaposition to Yom Kippur) stems from the fact that women don't dress up as nicely on Tisha BeAv as on Yom Kippur., however, it is preferable to refrain during the day, as well20Darchei Moshe 124:12. Sugah Beshoshonim 39:2..
Likewise, sleeping in the same bed is forbidden, even if both husband and wife are clothed, they have separate sheets and blankets and the bed is so large that there is no chance of their inadvertently touching21Mehaber 554:18, similar to niddah. Note that the Mehaber forbids sleeping in the same bed “the evening of Tisha BeAv.” See, however, Sugah Beshoshonim 39:5 in the name of the Beis Yosef where no distinction is drawn. Note also that the Darchei Moshe compares Tisha BeAv to Yom Kippur in regards to niddah..
When Tisha BeAv falls on Shabbos, it is nevertheless customary to refrain from marital relations22Ramo 544:19, Kitzur Shulchan Aruch 125:2., in addition to the mandatory separation on motzei Shabbos and Sunday.
If the wife’s night falls on Tisha BeAv which falls on Shabbos, she should go to the mikveh and relations are permitted23Magen Avrahom 554:20. Darchei Tahara page 199. Mishnah Beruroh 554:40. Kitzur Shulchan Aruch 125:2..
It is preferable to refrain from relations on the eve of the tenth of Av unless this is the night of the mikveh or he is leaving or returning from a trip24Mishnah Beruroh 558:2..
Other Calendar Concerns
As stated above, the most propitious time to perform marital relations is on Friday evening, whether for talmidei chochomim or other Jews.
The night of the mikveh, even when it falls on a weekday, has the same significance as Shabbos25Darchei Tahara page 200., in addition to being obligatory, as explained above.
Similarly, the evenings of Yom Tov and Rosh Chodesh have the same importance26Magen Avrahom 240:3. Darchei Tahara page 200., as well as the evening of Sheviyi shel Pesach27Darchei Tahara page 200..
On nittel nacht (the evening of December 24th) it is best to delay relations until after chatzos28Teshuvos Ubeorim Beshulchan Aruch page 416..
The marital act is permissible during chol hamoed Succos.
According to the AriZal29Mishnah Beruroh 240:7, Gefen Porioh 15:29., it is preferable to be strict by refraining on the following nights: the first night of Pesach, the night of Shavuos and the night of Shemini Atzeret unless, of course, this is her mikveh night. For someone who has not yet fulfilled the mitzvah of having children, these stringencies do not apply30Be’er Halacha on Mishnah Beruroh 240:7. Taharat Yisroel 240:11 adds, outside of eretz Yisroel, the evening of Simchat Torah and the second night of Pesach. His opinion does not seem to include the second night of Shavuos.. It is preferable to refrain from marital relations on the two nights of Rosh Hashonah31Brought in Be’er Hetev Orach Chaim 240:4. Refraining during the ten days of repentance is also praiseworthy, Be’er Hetev 240:4., unless, of course, if it is the mikveh night.
Refraining on these days is a stringency beyond the letter of the law. Therefore, in the event of this causing undue difficulties or transgression of other laws, it is preferable to have relations even on Rosh Hashonah. In such a case, the husband should make sure to go to the mikveh the following morning32Mishnah Beruroh 240:7..