Shabbat afternoons, especially in the winter months, often lend themselves to a rushed triathlon of Mincha, seudah shlishit and Ma’ariv. Many synagogues arrange their schedule so that Mincha is finished close to sundown; seudah shlishit is started just before sundown and completed at the earliest possible time to begin Ma’ariv. Often times, the schedule doesn't work out perfectly and Mincha either finishes after sundown or very close to it so that seudah shlishit cannot be eaten before sundown. The question then becomes: is it too late to start seudah shlishit?

In order to address this question, one must deal with three issues. First, when is the latest possible time to fulfill the mitzvah of seudah shlishit? Second, there is a prohibition of eating once the obligation to recite Havdalah sets in. What time period is included in this prohibition? Third, can the mitzvah of eating seudah shlishit override the prohibition to eat before Havdalah?

The Latest Time to Fulfill the Mitzvah
The time period between sundown (shekiat hachama) and nightfall (tzeit hakochavim) is known as bein hashmashot. This time period is considered safek yom v'safek laila (it is halachically doubtful as to whether it is considered day or night). Ostensibly, if one wants to fulfill the mitzvah of seudah shlishit with certainty, one must eat the third meal prior to sundown when there is no doubt as to whether Shabbat has ended. Once the sun sets, the day of Shabbat exists in a state of doubt, and the potential to fulfill the third meal of Shabbat is questionable.

Nevertheless, there is a concept of tosefet Shabbat which allows one to extend Shabbat. As previously discussed, there is a dispute whether one can fulfill the mitzvah of seudat Shabbat during tosefet Shabbat. Mishna Berurah 267:5, writes regarding tosefet Shabbat of the first meal that one should ideally eat a k'zayit of bread after tzeit hakochavim in order to satisfy the opinion that one cannot fulfill the mitzvah of seudat Shabbat during the time of tosefet Shabbat. R. Yehoshua Y. Neuwirth, Shemirat Shabbat Kehilchata (ch. 56, note 15), suggests that the dispute regarding the proper time for the first meal should be carried over to the third meal as well. Therefore, one should ideally eat a k'zayit of bread prior to sundown in order to realize a definitive fulfillment of the mitzvah. If one fails to eat a k'zayit of bread prior to sundown, one can potentially fulfill the mitzvah of seudah shlishit for two reasons. First, the bein hashmashot period might have the status of daytime. Second, perhaps the Halacha follows the opinion that one can fulfill the mitzvah of seudat Shabbat during tosefet Shabbat.

The Prohibition of Eating Before Havdalah
The Gemara, Pesachim 105a, states that if one is eating when the time for Havdalah arrives, one may continue eating. However, one may not start eating once this time arrives. Rif, Pesachim 21b, notes that the Gemara refers to the time period of bein hashmashot. During this time period one may not start eating, but one is not required to stop. Rabbeinu Asher, Pesachim 10:12, questions the need to interpret the Gemara as referring to bein hashmashot.

There is a dispute among the commentaries on Shulchan Aruch regarding Rabbeinu Asher's opinion. Magen Avraham 299:1 (as interpreted by P'ri Megadim, ad loc.), is of the opinion that Rabbeinu Asher does not distinguish between bein hashmashot and nightfall. One may not start eating during either of those time periods, and one may continue eating during both of those time periods. Taz, Orach Chaim 299:1, is of the opinion that Rabbeinu Asher allows one to start eating during the period of bein hashmashot. The entire discussion in the Gemara refers to the period after nightfall. After nightfall, one may not start eating, but if one started beforehand, one may continue. Taz adds that Rabbeinu Asher's opinion should be considered the normative opinion. He states that this is the justification for the practice of many people who start seudah shlishit after sundown.

Mishna Berurah 299:1, rules that one should follow the stringent opinion and should not start eating during bein hashmashot. However, he does not prohibit the entire bein hashmashot, but rather one-half hour prior to nightfall. R. Avraham C. Na'eh, Ketzot HaShulchan (ch. 94 note 6), notes that Mishna Berurah's ruling that one may not start eating within one-half hour of nightfall is following the opinion of Rabbeinu Tam that nightfall is (at least) seventy-two minutes after sundown. However, according to the Vilna Gaon, nightfall can be within one half hour of sundown. If so, one who follows the opinion of the Vilna Gaon would be prohibited from starting to eat one half hour before nightfall (of the Vilna Gaon) which is prior to sundown. [This discussion refers to a case where one has already fulfilled seudah shlishit. If one has not yet fulfilled seudah shlishit R. Na'eh allows the mitzvah of seudah shlishit to override the prohibition of eating before Havdalah, at least prior to sundown]. Nevertheless, R. Shlomo Zalman Auerbach (cited in Shemirat Shabbat Kehilchata ch. 56 note 17) suggests that since even those who follow the opinion of the Vilna Gaon will never actually recite Havdalah within one-half hour of sundown, they may start eating up until sundown.

Can the Mitzvah of Seudah Shlishit Override the Prohibition?
Mishna Berurah, Sha'ar HaTziun 299:2, states two reasons why one who has not yet fulfilled seudah shlishit may eat a meal during bein hashmashot. First, since there is a potential fulfillment of the mitzvah, one may rely on the opinion of Taz (in citing Rabbeinu Asher) and R. Zerachia HaLevi, Ba'al HaMaor, Pesachim 21b, that one may start eating during bein hashmashot. Second, the potential fulfillment of the mitzvah of seudah shlishit should override the potential prohibition of eating during bein hashmashot.

R. Moshe Feinstein, Igrot Moshe, Orach Chaim 4:69, and R. Shlomo Z. Auerbach, op. cit., are reluctant to allow the mitzvah of seudah shlishit to override the prohibition to eat before Havdalah. According to them one cannot start a meal within one-half hour of Havdalah, even for the purpose of fulfilling the mitzvah of seudah shlishit.

However, R. Feinstein (cited in The Radiance of Shabbos ch. 15 note 36) is quoted as having a different calculation in determining the latest possible time to start seudah shlishit. He claims that one may be lenient and eat seudah shlishit up to nine minutes after sundown. This is seemingly based on a ruling in one of his responsa (Igrot Moshe, Orach Chaim 4:62) applying the principle of sfek sfeika, double doubt, to laws contingent on sundown. The period of bein hashmashot is a period of inherent doubt whether it is day or night. Furthermore, the dispute between the Vilna Gaon and Rabbeinu Tam is applicable to the time of sundown as well as the time of nightfall. According to Rabbeinu Tam, the day does not end until approximately one hour after astronomical sundown. Therefore, so long as nightfall has not yet arrived according to the Vilna Gaon, (which R. Moshe assumes to be nine minutes after sundown) one may be lenient based on two mitigating factors: 1) Perhaps the Halacha follows Rabbeinu Tam and the day has not yet ended; and, 2) Even if the Halacha follows the Vilna Gaon, perhaps sundown is not the endpoint of the day. Therefore, for the first nine minutes after sundown, there remains a double-doubt as to whether the day is over, and one may treat that portion of the day as if it were daytime.

R. Mordechai Willig, Am Mordechai, Berachot no. 2, questions the application of sfek sfeika to this situation. This sfek sfeika is partially supported by the opinion of Rabbeinu Tam. However, Rabbeinu Tam's opinion is not followed in most communities, and therefore one can question its use as a mitigating factor. [See also, R. Ovadia Yosef, Teshuvot Yabia Omer, Yoreh De’ah 6:23:4, who discusses at length whether sfek sfeika is applicable in determining the time for the end of the day.]