Poster, it is not your responsibility to see if the person you gave tzedaka to, used it or not, deposited the check, or whatever. Do you keep track of how EVERYONE spends the money you give them (and it could be cash, too)? You have an achrayus to give tzedaka, and we take that to be maaser, because of the halacha of maaser. But you cannot control what someone does after the money leaves your hands. If you think that you have to be worried about that, then ask your rov if you are not considered to have given tzedaka if you give a check and it is not cashed. If that is true, you should only give cash to people.
My son and daughter-in-law use their maaser money (besides giving regular tzedaka donations) when they go to Chinese Auctions. If they actually win something, then they take the same amount of money that the winning ticket cost them, and give it to tzedaka a second time, because they don’t feel they gave tzedaka when they won something. So if they bought a $20 ticket and put it in the box for a trip to Florida and they win the trip – they give another $20 to Tzedaka. When they actually won a cash award from the auction, they gave maaser on THAT award as well.
Now here’s a question, and I am curious as to your responses. It is a little related to this topic, but in a different vein. If you enter a contest from a Yeshivah or Shul at a Chinese Auction to win, let’s say for argument’s sake, $20,000 cash, do you think it’s ok for the institution to deduct a maaser from the amount and only pay out $18,000 to you(no small piece of change, of course)? Do you feel that they should or should not be expecting that maaser money to go back to their mossad? Should the winner be allowed to decide for himself where he prefers to give his maaser money, or should he fargin them the 10%? Is it ethical for them to deduct it in advance without asking, or is this the norm?