The end of the day is composed of different stages. First there is sheki’ah, the end of definite day. This is followed by bein hashemashot (lasting between 13.5 and approximately 17 minutes), which is treated as a safek[1] with regard to whether it is daytime or nighttime. After bein hashemashot comes tzeit hakochavim,[2] which is definite night.
There are two major approaches among the poskim as to the definition of what the gemara calls sheki’ah, which literally means sunset: One approach is that it is what we call astronomical sunset (often called the Gra’s opinion);[3] the other approach is that sheki’ah is at a significantly later point, at which the sun goes well under the horizon, around an hour after sunset (often called Rabbeinu Tam’s opinion).[4] This machloket has many direct and indirect halachic implications (including when Shabbat begins and ends), and it impacts on the time for Mincha as well, as according to the latter opinion, one may daven Mincha for close to an hour after sunset.
There are two opinions in the mishna[5] regarding the end time for Mincha – until plag haMincha[6] or until the erev (evening). The Shulchan Aruch[7] defines the latter opinion, which most people now regularly follow, as meaning until the layla (nightfall).[8] The great majority of us follow the opinion that astronomical sunset is halachic sheki’ah, in accordance with the opinion of the Gra. Therefore, the Mishna Berura[9] instructs one to daven Mincha before sunset. However, because there are opinions that one may daven Mincha after sunset, he writes that in times of great need, there is room for leniency regarding davening Mincha after sunset.[10] This is especially true if one is davening within the first thirteen and a half minutes of sheki’ah, which, according to the main opinion, is still bein hashemashot.[11]
Is it sufficient for one to merely start Mincha by the cutoff time, or must he also finish it by then? Most poskim posit that as a rule, obligations must be completed by their time limit, and this rule also applies to Mincha.[12] Only a minority suggest that beginning on time suffices.[13] Accordingly, many poskim maintain that it is better to finish Mincha before sunset without a minyan than to finish it after sunset with a minyan.[14] One could argue that given the minority opinion of Rabbeinu Tam that sheki’ah is much later than sunset, in addition to the minority opinion that it is sufficient to merely start Mincha before sheki’ah, there is reason for leniency, and one may therefore start before sunset and finish after it.[15] This is not a simple claim for those who do not subscribe at all to Rabbeinu Tam’s opinion, however.
Even if the silent Shemoneh Esrei is completed before sheki’ah, we must still consider the elements of Mincha that follow, such as chazarat hashatz. Fundamentally, there is little difference between the timing of Shemoneh Esrei and that of chazarat hashatz, which, after all, is supposed to serve as Shemoneh Esrei for certain individuals and/or the tzibbur. On the other hand, if everyone has already finished his personal Shemoneh Esrei, the stakes regarding chazarat hashatz can be considered lower. It is therefore not surprising that there is a machloket among the Acharonim[16] regarding whether it is better to recite a shortened chazarat hashatz (often called Heiche Kedusha),[17] which is considered less than ideal,[18] or to finish chazarat hashatz after sheki’ah. In any case, several poskim write that if one is present in a shul in which chazarat hashatz is being recited after sheki’ah – and even if it is recited after tzeit hakochavim according to one’s personal practice – he may answer amen.[19]
Nefilat apayim (putting our heads down) for Tachanun is not performed at night,[20] but the Mishna Berura[21] writes that it can be done during bein hashemashot. He further notes that one can still say the words of Tachanun at night, even though he would not do so with nefilat apayim.[22] Notably, however, several authorities report a minhag Yerushalayim not to recite Tachanun at all after sheki’ah.[23] Reciting Kaddish Titkabel (after chazarat hashatz) after sheki’ah is not a problem, regardless of whether one finished chazarat hashatz before or after sheki’ah.[24]