Haircut on the Thirtieth Day

A mourner who was reprimanded on the thirtieth day after his father's passing, can he get a haircut on the thirtieth day?

He can get a haircut on the thirtieth day after being reprimanded. (Except for those who follow the custom of not getting a haircut for three months.)

In the Gemara Moed Katan, page 19, the sages and Abba Shaul debate whether a part of the day is considered as a whole day or not, and it is stated in the Gemara that the law follows Abba Shaul, who says that a part of the day is considered as a whole day. Similarly, the Shulchan Aruch rules in Siman 395, paragraph 1: "When the comforters rise from the mourner on the seventh day, all things that are forbidden during the seven days are permitted, as a part of the day is considered as a whole day, whether it is part of the seventh day or part of the thirtieth day, when the sun rises on the thirtieth day, the decree of thirty days is annulled". And the Beit Yosef wrote in the name of the Gaon Meiri, and so wrote the Reak Eiger in the name of Elia Zuta (Siman 548), and so wrote the Sheyarei Knesset Orach Chaim, Siman 548. That even reprimand concerning one's father and mother is effective on the thirtieth day.