I just learned the hard way, so I’m passing on my $25 lesson to you:
Before you close a credit card account, redeem any rewards available to you.
Here’s what happened in our case: Marc and I recently decided to switch rewards cards, and opened a new credit card account and closed the old one. It never occurred to me before we closed the old one to redeem the points for a $25 gift card and of course, now that the account is closed, the points have vanished. (Believe me, I did try to redeem them when I was paying the final bill and saw the points total at the top, which was my mental trigger. After I logged in, the screen said something like: Would you like to open a different type of account to earn points?)
I hate wasting money, but fortunately, the lesson wasn’t too expensive. After all, the whole reason we were switching cards was because we didn’t use the original card enough to accumulate many points.