I taught at a Yeshiva for several years and being that the Yeshiva was in bad financial state I am still owed quite a bit of money that was promised in my contract. May I deduct this amount from future Maaser that I owe?
There are different opinions about this, however many poskim say that it is permitted to deduct the money that the poor person owes him from maaser, instead of collecting the money. However, this only applies if it is possible for him to actually collect the money from the poor person, i.e. the person isn’t bankrupt, or didn’t die. Also, if the lender gave up on receiving the money, he will not be able to do this.
Rema Y:D 257-5, Shach ibid 13, R’ S. Z. Auerbach Teshuva 21 (end of sefer B’orach Tzadakah, Yaskil Avdi Y:D 1-13 (2-2,) Bais Din Shel Shlomo Y:D 1 Hilchisa Pesikta 15, Tesuvos V’hanhagos1-560- 11, B’orach Tzedakah 11-108. See Shach ibid 12, Igros Moshe Y:D 1-153 that says differently.