Bentching over Wine

Question: Our second son recently turned bar mitzva and so we now have a zimun. Is it necessary to bentch over a kos of wine each time?

Answer: The Gemara (Pesachim 105b) teaches that one should bentch with a kos of wine. There is a machlokes among the rishonim as to when this applies.

Tosafos (Pesachim 105b) quotes the Rashbam and Midrash (Shocher Tov 3:8) who maintain that even one eating alone must not bentch without wine. The Tur (OC 182) writes that we follow Tosafos and adds that one who does not have wine for bentching, should not wash for bread.

The Hagahos Maimonios (Berachos 7:60) and Kol Bo (25) write that according to others, this only applies when one has a zimun of (at-least) three. Tosafos (ibid.) notes that this is the practice.

Nonetheless, Rambam (Berachos 7:15), the Rif (Pesachim 105b) and the Rashba (Berachos 52a) write that this is not an obligation, regardless of how many people are bentching.

The Shulchan Aruch (OC 182:1) records all of these opinions. The Rema adds that it is meritorious to bentch over wine. The Mishna Berura (128:1) writes that although the Shulchan Aruch does not determine how we pasken, it is considered meritorious to do so, but only when one has a zimun. R’ Moshe Feinstein (Igros Moshe OC 4:69:1) writes that the halacha follows Rambam and that the Rif, and there is no requirement to bentch over wine. The Aruch Hashulchan (OC 182:1) notes that people are not particular to bentch over a kos, particularly as wine is so expensive. Nonetheless, it is commendable to do so on Shabbos and Yom Tov.

In conclusion, it is not necessary to bentch over wine when one bentches with a zimun, but it is commendable to do so, particularly on Shabbos and Yom Tov.