Question Summary:
Can I change my surname to my husband’s surname?

Question Detail:

My question is I’ve been married for nineteen years now, and have not since changed to my husband’s surname. Please guide as to whether it is best for a woman to change to her husband’s surname.?
JazakAllah

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful. 
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
A married woman may maintain her own surname or adopt her husband’s surname. She may do whatever she feels is practically best for her to do. [i]
If her husband wants her to adopt his surname, it is advisable for her to consider her husband’s wish in doing so. [ii]
 
And Allah Ta’āla Knows Best
Abdullah Syed Sajid
Student Darul Iftaa
Houston, TX, USA 
Checked and Approved by,
Mufti Ebrahim Desai.