It is not permissible to deduct the costs of transferring zakaah from the zakaah

In the answer to question no.
43146 we stated that zakaah may be
taken from the land where the wealth is, and it is permissible to transfer
it to another country in cases of need or where that serves a purpose, such
as if the poor in the land to which it is transferred are in greater need,
or are relatives of the one who is paying zakaah, and so on. 

Secondly: 

The owner of the wealth is obliged to make sure the zakaah
reaches those who are entitled to it. Based on this, if getting it to the
poor requires travelling and other costs, these must be paid for by the
owner of the wealth, and it is not permissible to deduct them from the
zakaah. 

Al-Nawawi (may Allaah have mercy on him) said in
al-Majmoo’, 6/213: 

As it is
permissible to transfer zakaah (to another country), or may be obligatory,
the costs of doing so must be borne by the owner of the wealth. End quote. 

Al-Mardaawi (may Allaah have mercy on him) said in
al-Insaaf (7/174): 

The cost of transferring the zakaah is to be borne by the
owner of the wealth. End quote.  

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was
asked: A person has been asked to take some zakaah abroad at the personal
level; is it permissible for him to be given the travel expenses from the
zakaah, knowing that he cannot afford to pay for that himself? 

He replied: 

It is not permissible for
him to take anything from the zakaah for this trip, because what the person
who owes zakaah must do is to send it to the poor with his own money. If he
wants to go to a place where he has to spend on travel expenses, then he
should take them from the owner of the money, and the rights of the poor
must be given to them in full. End quote.

Majmoo’ Fataawa Ibn ‘Uthaymeen,
18/369.