An invoice I received from my supplier shows a much lower amount than what my records state. When I contacted him, he responded that I must have miscalculated, as he checked his records and is certain that I don’t owe any more than what I was billed.

Q: Am I obligated to assume that his computer records are inaccurate and pay him what I think I owe him? What is the halacha if, at some point in the future, he realizes that I do, in fact, owe him more?

A: The issue here is the meaning of a creditor’s declaration that he is not owed money. Is he stating a fact or forgiving his right to collect that debt? If he is merely stating what he believes to be fact and it turns out that he was wrong, he would be able to collect. If, however, his declaration is a forgiveness of the debt, a subsequent claim that he was mistaken is irrelevant, since the debt was forgiven.

Shulchan Aruch (C.M. 75:11) rules that when a creditor denies the existence of a debt, even mistakenly, the debtor is exempt from paying. Halachically, such a declaration is not an incorrect statement of fact; it is rather considered a conscious act of forgiving the loan. When a debtor states that he owes money, the creditor should research the matter. By deciding to disregard the debtor’s admission and declaring that he is not owed, the creditor is forgiving the loan (Tur ibid.). In such a case, the debtor does not have to pay the money that he owes even to fulfill a heavenly obligation - latzeis yidei shamayim - because the loan was forgiven.

If the creditor later claims that he erred, the debtor is not obligated to pay him; the creditor’s original declaration released him from any responsibility to repay. However, if there is reason to think that the creditor’s statement is based on an honest mistake, e.g. the debtor knows that the creditor would not lie and seemingly forgot this debt, he should pay latzeis yidei shamayim. If it is possible that the information was misplaced, the debtor may be obligated to pay. Additionally, if the issue involves an object rather than money, the debtor must return the object he knows belongs to the creditor (Aruch Hashulchan ibid 15).

In the event that the creditor is merely uncertain whether he is owed money, the debt remains in force. Nevertheless, as long as the creditor does not ask to be repaid, the debtor has the right to assume that the creditor forgave the loan (Tumim 29). The rationale is that since the creditor could claim the money based on the debtor’s admission and he doesn’t, it may be assumed that he has forgiven the debt.

Thus, if the creditor denies that you owe him as much as you say, it is as if he has forgiven the debt. If his claim is based on his records, it is not considered a definitive denial, and if he were to return and claim that his records or the computer were mistaken, you would be obligated to pay that debt.