He works as a trustee in a bank and he may have to write cheques for riba-based loans
Question

                I work as a trustee in a bank and I make out cheques. Sometimes the amount in the bank account does not cover the amount of the cheque, so the cheque is handled by the bank as a loan with interest to the institution. Is there any sin on me if I write the cheque? Also is there any sin on the person who deposits the cheque?.
Praise be to Allah.
    It is not permissible to deal in riba (usury, interest) or to 
    help with that in any way, shape or form, because Allaah says 
    (interpretation of the meaning): 

    “Help you one another in Al‑Birr and At‑Taqwa (virtue, 
    righteousness and piety); but do not help one another in sin and 
    transgression. And fear Allaah. Verily, Allaah is Severe in punishment”

    [al-Maa’idah 5:2]

    It was narrated that Jaabir ibn ‘Abd-Allaah (may Allaah be 
    pleased with him)said: The Messenger of Allaah  (peace and blessings of 
    Allaah be upon him) cursed the one who consumes riba and the one who pays 
    it, the one who writes it down and the two who witness it, and he said: they 
    are all the same. 

    As for the cheque which constitutes a loan with interest, it 
    is not permissible to write it or help with it. The one who does that is 
    exposing himself to the curse and being cast out from the mercy of Allaah. 

    The scholars of the Standing Committee for Issuing Fatwas 
    were asked: What is meant by the one who writes down riba, as mentioned in 
    the hadeeth of Jaabir that was narrated by Muslim, where he said: the 
    Messenger of Allaah  (peace and blessings of Allaah be upon him) cursed 
    the one who consumes riba and the one who pays it, the one who writes it 
    down and the two who witness it, and he said: they are all the same? Is the 
    one who writes down riba the one who just writes that document? Or could it 
    include any individual who has nothing to do with the riba institution, but 
    because of his work as an accountant, he adds and subtracts numbers in 
    documents that have nothing to do with the original document of riba? Is 
    that accountant regarded as writing down riba, or does this wording apply 
    only to the one who writes that document and does that not apply to anyone 
    else and does the curse not apply to anyone else? 

    They replied: 

    The hadeeth about the one who writes down riba being cursed 
    is general in meaning, and it includes the one who writes the original 
    document, the one who copies it if the original wears out, and the one who 
    records the amount in records of accounts, and the accountant who works out 
    the rate of interest and adds it to the original sum, or send it to the 
    depositor, and so on. And Allaah is the source of strength. May Allaah send 
    blessing and peace upon our Prophet Muhammad and his family and companions. 

    End quote from Fataawa al-Lajnah al-Daa’imah. 

    So beware of taking part in this grave sin. 

    And Allaah knows best.