I took out a loan from a bank for a considerable amount of money, which was later negotiated down to about 10%, with the rest forgiven.
The loan was for schooling, but was given to me in cash, and was used for personal expenses.
Am I obligated to give ma’aser for the forgiven amount?
I am assuming that the reason you negotiated the loan was because of your difficult financial situation.
Essentially the money was given to you to use, so you would have to give maaser from it, either when you got the loan, or from the money that you earned to pay it back. In your case the bank gave you the loan and didn’t collect the money so it was like a present, so you would give maaser from it. However if your financial situation is such that the bank was willing to forgive a considerable amount of the loan, you would not have to give maaser at all, because of your financial situation.