AVOID HAVING A HAIRCUT DURING PERIODS OF MOURNING
Question: Is it alright to have a haircut on our birthday?
Answer: It’s up to you. It’s good to have a haircut as it makes one appear neat and tidy. Typically, we must avoid having a haircut on the Ching Ming Festival, Zhong Yuan Festival (Ullambana Festival) and Dong Zhi Festival (Winter Solstice), because these are the days we mourn and commemorate generations past. It is a no-no to have a haircut during periods of mourning because it is disrespectful to our elders.
Source: Master Jun Hong Lu’s Discourse (Question 262), 31 October 2018