Is Cutting Hair Haram for Muslim Women?
Question

I have often heard that it is not permissible for a woman to cut her hair at all, according to the rulings of Islam. I want to understand the reason, because I think that she needs to trim her hair from time to time. Can you explain this issue in detail? 
I also heard that the woman is required to grow her hair as long as possible, and she should not cut it or shave it, because it will be a cover for her on the Day of Resurrection when all people are gathered naked. Is this true, and is there any evidence for it?
Praise be to Allah.When is cutting hair prohibited for women?
What the scholars have stated is prohibited with regard to a woman cutting her hair , is the following:

If she is going to flaunt it in front of non-mahram men.
If by cutting her hair, her intention is to imitate disbelieving women or immoral women.
If she cuts her hair in a manner resembling men’s hairstyles.
If her hair is cut by a non-mahram man, as happens in sinful salons.
If she does that without her husband’s permission.

The reason for this prohibition in these instances is quite clear, and there is no cause for confusion. The wisdom behind this prohibition is also quite clear.
When can Muslim women cut their hair?
If the woman’s aim is to adorn herself for her husband and endear herself to him, or her aim is to reduce the trouble of caring for long hair, or other reasonable, permissible aims, then there is nothing wrong with her doing that, according to the sound scholarly view. This is because the basic principle with regard to matters of custom and tradition is that they are permissible unless there is evidence that something is prohibited. 
There is nothing in Islamic teaching to indicate that it is not allowed to cut a woman’s hair; rather there is a report which indicates that it is permissible. This is the hadith of Abu Salamah ibn ‘Abd ar-Rahman (may Allah have mercy on him) who said: The wives of the Prophet (blessings and peace of Allah be upon him) used to cut their hair so that it came down no lower than their earlobes.  (Narrated by Muslim, 320)
It was also said that the original Arabic of this report may be understood as referring to hair that is slightly longer than shoulder length.
Imam an-Nawawi (may Allah have mercy on him) said:
“This indicates that it is permissible for women to cut their hair .” (Sharh Muslim, 4/5)
Shaykh Ibn ‘Uthaymin (may Allah have mercy on him) said:
“For a woman to cut her hair was regarded as makruh (disliked) by some scholars, and some scholars said it is haram (forbidden), and some scholars said it is permissible.
So long as there is a difference of scholarly opinion concerning the matter, then we should refer to the Quran and Sunnah. Up until this moment I do not know of anything which would indicate that it is forbidden for a woman to cut her hair.
Based on that, the basic principle concerning this matter is that it is permissible, and that local custom may be followed in this regard. 
In the past, women were keen to have long hair and would be proud of it, and they would not cut it unless there was a shar‘i reason or health-related need to do so. 
Now things have changed, so the view that it is forbidden is weak and there is no proof for it. The view that it is disliked needs further reflection and examination. 
The view that it is permissible is closer to the basic principles of Islam. Muslim narrated in his Sahih that the wives of the Prophet (blessings and peace of Allah be upon him) used to cut their hair so that it came down no lower than their earlobes.
But if a woman cuts her hair too short , so that it looks like a man’s hair, then this is undoubtedly haram, because the Prophet (blessings and peace of Allah be upon him) cursed women who resemble men.
Similarly, if she cuts it in a style that resembles the hairstyles of disbelieving women and immoral women, then whoever imitates a people is one of them.
But if she only cuts it a little, so that it does not go to the extent of resembling men’s hairstyles, and does not resemble the hairstyles of immoral women and disbelieving women, then there is nothing wrong with that.” (Fatawa Nur ‘ala ad-Darb (Fatawa az-Zinah wa’l-Marah/Qass ash-Sha‘r) 
Will women be covered with their hair on the Day of Judgment?
What is said about a woman’s hair covering her on the Day of Resurrection is something for which there is no evidence in the Sunnah and reports, and we have not found this in the words of the scholars. So we should beware of transmitting and believing this idea before checking whether it is sound and proven in the religious texts.
For more about cutting hair for Muslim women, please see these answers: 1172 , 106290 and 1191 . 
And Allah knows best.