Working on programs which do the accounts for a
    company and include riba
Question

                A person is working as a
      computer programmer, and the computer programs on which he works keep stock of what the
      company has in its warehouses, how much has been sold, how much is left. They also keep
      track of maintenance, sales, employees’ salaries, etc. This program also calculates
      the interest on deposits held by this company, but the ratio of haraam work to permissible
      work dealt with by the program is very little, no more than 5%. This person works with the
      entire program and cannot work only on one part and ignore the other part. Is it
      permissible for him to work on this program or not?
Praise be to Allah.We put this question to Shaykh Muhammad ibn
    Saalih al-‘Uthaymeen, may Allaah preserve him, who replied as follows:
It is not permissible to work for this company unless he puts
    the condition that he will not have to deal with riba, meaning that he should not record
    anything having to do with riba.
Question:
This computer program runs calculations by pressing buttons,
    so the accounts for all budgets are done by pressing buttons. They are not recorded on
    paper, for example, so that he could record this and not record that. Everything is done
    by pressing buttons, including those that involve riba. It is not possible to separate
    between them.
Answer:
To be on the safe side, he should not work there, and Allaah
    will send his provision. And Allaah knows best.