Do You Have to Shave Your Head for ‘Umrah?
Question

I have done ‘Umrah twice with my family. The first time was seven years ago, and the second time was last year. In both times I just shortened my hair, I did not shave it. As my father used to follow the fatwa that permits one to shorten his hair only, so both times we just shortened our hair from the back and sides, we did not even shorten all of it.
I have read in the answer number (10713 ) that if a person did that out of ignorance, then he should take off his regular clothing (and put on ihram) and shave his head completely or cut his hair. 
But thus I will have to shave my head twice, what shall I do if I want to make up for the mistake? I have heard before that it is permissible to just shorten the hair in the fatwa of Hajj and ‘Umrah.
Praise be to Allah.The one who does `Umrah has to shave his head or cut some of his hair , but shaving is better. He has to remove hair from all of his head and it is not sufficient to remove hair only from part of the sides of the head , according to the more correct opinion. This is the view of Malik and Ahmad. Abu Hanifah (may Allah have mercy on him) was of the view that it is sufficient to remove hair from only one quarter of the head. 
Al-Shafi`i was of the view that the minimum that is sufficient is three hairs, to be shaved or cut. 
But all are agreed that it is better to shave the whole head rather than cutting the hair, because Allah says (interpretation of the meaning): “having their (head) hair shaved and cut short” [al-Fath 48:27], and the word head means the whole thing. And it is proven that the Messenger of Allah (peace and blessings of Allah be upon him) shaved all of his head. See: al-Mawsu’ah al-Fiqhiyyah (18/98). 
The argument of the Malikis and Hanbalis is that the Prophet (peace and blessings of Allah be upon him) shaved all of his head, which explains what is meant by shaving.   
Ibn Qudamah (may Allah have mercy on him) said in al-Mughni (3/196): 
He has to cut or shave all of his hair , and the same (for cutting the hair) applies to women. This was stated by Imam Ahmad, and it was also the view of Malik. It was narrated from Ahmad that it is sufficient to (cut or shave) some of it. al-Shaf’i said: It is sufficient for him to cut three hairs. Ibn al-Mundhir was of the view that it is sufficient for him to do what may be called cutting short. The fact that it is obligatory to include all of the head is indicated by the words of Allah (interpretation of the meaning): “having their (head) hair shaved and cut short” [al-Fath 48:27], which is general in meaning and implies all of it. And the Prophet (peace and blessings of Allah be upon him) shaved all of his head which explains what is meant by shaving. End quote. 
It says in al-Taj wa’l-Iklil (a Maliki book) (4/181): Whoever shaves his head or cuts his hair, let him (shave or cut hair from) all of his head; it is not sufficient for him to remove hair from only part of it." 
But if a person removed hair from only part of his head , following the view of those who hold this opinion, then he does not have to do anything now, because it is a matter that is subject to ijtihad and the scholars differed concerning it. Based on that, you do not have to enter ihram again and shave it or cut it again. 
But if you do `Umrah or Hajj in the future, your cutting the hair or shaving should include all of the head.
And Allah knows best.