Inner Space Excerpted and adapted from a shiur by HaRav Chaim Weg January 13, 2022…
ASKING THE BORROWER TO CASH A CHECK
A person asks his friend for a loan. His friend agrees to lend him money, but since he only has a check, he tells him to cash the check, borrow the amount he needs, and return the rest.
A fellow asks his friend for a loan. The would-be lender claims he has no money, but gives the borrower some merchandise to sell with the right to borrow the requested amount from the sale.
The lender asks the borrower to mail his payment every month. This requires the borrower paying the additional cost of a stamp.
Do any of these cases involve ribbis?
In case #1 the borrower is allowed to cash the check if no great effort is involved. However, if the check requires that he go to the bank, such as a check for a small amount which most check-cashing stations will not accept, the lender would be transgressing ribbis mukdemes since he is forcing the borrower to go to the bank on his behalf.
Case #2 would definitely be considered ribbis mukdemes due to the tirchah, and therefore prohibited, unless the lender pays the borrower for the tirchah of selling the merchandise on his behalf. Alternatively, if the lender accepted full responsibility for the merchandise if damaged or lost, it would be permitted even without reimbursement for tirchah.
Case #3 is permitted, as is any tirchah the borrower has to go through to pay back the loan. Borrowing money requires that one assure the money is repaid, even if it involves the cost of traveling to the lender’s house to repay him, or for the postage on the payment envelope.