For sure giving Khums money to a reliable and authentic representative or to owner of ijaza is important same as it is obligatory to release the Khums money from our net savings.
As for as it’s correct and legal use is concern, yes a person is not allowed to use it for his/her personal needs unless he/she has permission from the office of the Marja.
Now if any institution has Ijaza of Sahme Imam (any percentage ) then the amount it is taking from the Muqallid has to divided fairly and rest of the amount should be given to the office of that marja. But in some cases few institution, they get Ijaza of a specific figure e.g. they have permission that in one year they can take let’s say 1 million INR, now if their collection goes more than 1 million, rest they have to sent to their marja otherwise if they have received 5 lakhs they can use all.
Iff they have for example a school, of course they have to use the received amount for rent, electricity bill and many more bills including salaries of their staff. There is no issue in that but same time all has to be very clear and accessible for every donor and even for normal Mo’menins. Also authorities of that institution are not allowed to use single penny for their personal need.
In short it is very important for a Muqallid that he has to know where he is giving the Khums money really do they have Ijaza from his Marja and what is the mode of Ijaza they I mean their purpose and percentages and do they really working on ground or just they have opened the offices and working on paper only. There are many institutions they truly working for community but sometimes unfortunately there some who just making it a their business.