The only fast day that can fall on erev Shabbat is Asara b’Tevet, which is always observed on the correct calendar date. In this situation, mikveh night can fall out on a Friday night at the end of the fast.
The fast ends at nightfall, after Shabbat has begun, so a woman needs to hear or recite kiddush before breaking her fast.
Sephardi halachic authorities often permit immersion on Friday night as of shekiah (halachic sunset). A Sephardi woman who lives near the mikveh can thus immerse just after shekiah and arrive home around nightfall.
Ashkenazi rulings typically, however, do not permit immersion prior to nightfall. Some Ashkenazi women may have little difficulty immersing as usual as of nightfall, even if this extends the fast a bit.
For some Ashkenazi women, though, extending the fast until after immersion may prove challenging (and may delay the household’s Shabbat meal). Sephardi women who live farther from the mikveh could face similar difficulties.
In a community where a mikveh attendant is able to open the mikveh for a “second shift,” women could arrange to immerse later in the night, after the Shabbat meal. Rav Kenneth Auman follows the view that a woman in this situation would still be permitted to eat meat at the Shabbat meal, as long as she cleans her teeth well prior to immersion.
If immersion later that night is not possible, Rav Auman would consider this to be a pressing need, so that a woman would be permitted to either:
- Immerse as of shekiah (even if this is not her usual custom), taking care not to see her husband prior to nightfall, or
- Break her fast before immersion. She would make kiddush for herself at nightfall, eat—even just mezonot—following kiddush, and then clean her teeth and immerse.
Please see these pages for general information on Shabbat immersion:
Shabbat & Yom Tov Mikveh
Mikveh & Makeup on Shabbat & Yom Tov
