Two questions regarding ribbis:
1. May someone make an estimated advanced payment if they are trying to avoid being undercharged? Sometimes the computer that tallies a weekly delivery order undercharges on the delivery fee. I have lately been trying to call and mention that it was undercharged, but before trying to understand the laws of ribbis in depth, I had sent the company a check for a bulk amount to cover any computer under-charges in case I forgot to call. May I consider that any money given is to cover the appropriate charges and then have in mind that the extra is a gift from one Jew to another, or does this act transgress ribbis?
2. Regarding paying for an item that was purchased years ago, and the charge did not go through. I do not remember what I was charged for the item, and after doing research in my records, and email, I do not know the exact amount paid. The company is selling the same item, years later, probably at a higher price than I paid. May I pay the higher, current market price having in mind that any extra is also a gift (just to satisfy peace of mind that I paid what was due), or would this transgress ribbis?
3. If either of these two examples do transgress ribbis, how should example 1 be rectified and how should example 2 be handled if I would like to pay for an item that I am not sure the exact amount?
Thank you sincerely.
In question 1 the reason you are paying extra is not because you got a loan from the company, but because you want to make sure that you paid all the charges. Therefore it isn’t an issue of ribbis, because you are not paying it because of the late payment, rather because you want to make of the money you might owe.
In question 2, the amount of money you owe is what the item cost when you bought it, not the current price. If you bought the item from the company you might be able to track the price that was supposed to be paid. Alternatively you can ask them. They might just say to forget about it, or they might tell you what the price was years ago. If this doesn’t work you can pay the current price, for the same reason as in question 1.