Lechem Mishna: Third Meal
Question
Do i need lechem minshnah for the third meal, shalos seudos?
Answer
Shalom!
Thank you for your question.
According to the Shulchan Aruch one must have lechem mishneh for Shalosh Seudos. In fact, one is to have lechem mishneh at every meal one eats on Shabbat even if one eats 4 or 5 meals!
Even though the Rema quotes a custom to only require one loaf for Shalosh Seudos. This is based on the Talmud Yerushalmi that says that on Fridays everyone received 4 loaves of bread. One loaf was eaten on Friday during the day, one on Friday night, and one on Shabbat morning. This means that there was only one loaf left for Shalosh Seudos!
Nevertheless, the halacha is that one is to have lechem mishneh not only at Shalosh Seudos, but for all the meals that one has on shabbos.
Source
O.C. 274:1, Mishna Brura 274:1, OC 291:4.