Praise be to Allaah.
In the case of khula‘, it is not stipulated that the word
of divorce be uttered; it is an annulment and not a divorce (talaaq)
according to the correct opinion. When khula‘ is done, the wife is
irrevocably divorced, and the husband does not have the right to take her
back except with a new marriage contract.
Khula‘ may be given in return for financial payment, such as
if the wife returns the mahr to the husband or gives up some of the delayed
portion of the mahr. See the answer to questions no.
The qaadi may oblige the husband to divorce his wife by
talaaq or by khula‘, if he finds cause to do so, such as if the wife is
being harmed. If the khula‘ or divorce has been done through the court, the
husband has no choice but to refer back to the court and try to convince the
court to overturn its decision or to get an official fatwa from the relevant
department in his country stating that the khula‘ is invalid, and submit
this fatwa to the court.
And Allah knows best.