What prevents taking an agency fee in advance when cashing a check for a person who does not have identification documents?

It is not permissible for the questioner to give the check's value from his own money to the check's owner with the intention of claiming it back later, because this falls under the ruling of a lender, and it is not permissible to combine a loan with any contract of exchange. Similarly, it is not permissible for the questioner to buy the check for himself, so that he owns it, whether he collects it or not. This is known as discounting checks, which is not permissible according to Islamic law because it is the sale of a deferred debt.