Haircut at the End of the Year During the Three Weeks

A person mourning his deceased father is being reprimanded for his overgrown hair during the Three Weeks when haircuts are prohibited. Is he allowed to be lenient and get a haircut?

He is permitted to have any haircut until Rosh Chodesh in a manner that would no longer be subject to reprimand.

Responsa Chatam Sofer, Part 2, Yoreh De'ah, Siman 347: "Regarding someone who is in mourning for his father and mother, and it coincides with the mourning from the 17th of Tammuz onwards, what is the ruling on haircuts? I have already stated in some responses that the measure of reprimand mentioned in the sources refers to those who only shaved their head hair, and it suffices to shave every three months. However, for Ashkenazim who are accustomed to shave their beards, it is more unkempt and repulsive within thirty days, and it leads to more reprimand, even within twelve months for head hair. Therefore, if the measure of reprimand coincides with the 17th of Tammuz and the measure of reprimand with thirty days, it is the same rule. And in the Talmud, it is said that if mourning days follow one another, he may ease his head with a razor, but not with scissors. However, regarding the haircut from the 17th of Tammuz, the Bach in Siman 551, paragraph 7, permitted even with scissors, and this was brought by the Magen Avraham there at the end of Siman 18. Nevertheless, regarding his father and mother, since it is due to reprimand, it seems to me that one should not be so lenient as to cut like a groom among mourners, but should have any haircut on the 18th of Tammuz in a manner that would no longer be subject to reprimand, as it seems to me. And I found support for my opinion in the book Noda B'Yehuda, Part Orach Chaim, Siman 13, where a distinction is mentioned between a beard for Ashkenazim and head shaving for Poles, see there, as it seems to me, I have written."