Is it permissible to place a sum of money as a fixed-income deposit in a usurious bank in order to pay off monthly installments of a usurious loan, with the aim of alleviating the burden of the installment on one's salary, while not taking any of the deposit's interest?

If the bank is usurious (Riba-based), it is not permissible to deposit money with it for investment and to take usurious interest to pay off an installment, as this falls under a forbidden usurious contract. The Prophet, peace and blessings be upon him, cursed the one who consumes Riba, the one who feeds it, its scribe, and its two witnesses. However, if the bank is Islamic and adheres to Sharia guidelines, then there is no objection to investing money with it to utilize the profits in paying off the installment.