What is the ruling on dealing with a contract in which the seller undertakes to supply goods to the buyer after 15 days for an agreed-upon amount that the buyer pays 10 days after receiving them, with a penalty clause for the party who delays delivery or payment? And is it permissible to work as an accounting manager in a company that deals with such contracts if they are forbidden?

If the sale is for a thousand specific, existing, but absent pieces, it falls under the category of selling an absent, described item. In this case, delaying payment is permissible. However, the buyer is not allowed to pay a penalty for late payment because it constitutes usury (riba). Nevertheless, it is permissible to obligate the seller to pay a penalty for late delivery of the sold item, as compensation for damages.

If the sale is for a described item that is a liability (in the abstract), it falls under the category of a salam (forward) contract. In this case, the price must be paid at the contract assembly. It is not permissible to obligate the seller to pay a penalty for late delivery of the sold item because it is a debt.

Therefore, if you can work for the company without directly engaging in or assisting in prohibited acts, there is no harm in doing so. Otherwise, you must leave the job.