What is the ruling on banking transactions for a company based on commissions and interest, and what is the ruling on working for it, and the money earned from it, and what is the advice for the employer?

There is no harm in the commission taken for a letter of guarantee if it is in accordance with the actual costs of its issuance. As for the letter of credit, if it is fully covered by the client, it is an agency for which a fee may be taken. However, if it is not fully or partially covered, it is a loan for which a fee may not be taken. The other transactions mentioned are forbidden due to the suspicion of a loan that brings benefit. Working in forbidden fields is unlawful because it constitutes aiding in sin, while working in permissible fields is permissible. Accounting and employee work take the ruling of the field in which they are conducted. Repentance from what is forbidden is obligatory, and one must dispose of the money earned from it by spending it on charitable causes. Furthermore, it is obligatory to denounce forbidden transactions by forbidding the employer from them.