My neighbor next door has a gan where I sent my kid. The monthly payment is 388 shekels. The last month I paid her she mistakenly wrote down that I paid her 300 shekels. My husband and I remember that I paid her 400 shekel. She claims I still owe her 88 shekels. Can I pay her the money she claims I owe and deduct it from my maaser (she is not well off and has a large family). My kid has been going to this gan for over a year and we never paid less than what what was owed that month (sometimes more and it was carried over as a credit)
If you are sure that you don’t have to pay the money and bais din would not be able to force you to pay the money, and it is also clear to you that you already paid it, then you can use maaser money to pay your neighbor.