If you try to get a tax receipt for a donation of miles or points, BE CAREFUL, 'cause you're starting down a long and dangerous road. If you are going to assign those points a value (whatever it is) to be set off against your other income, you'll most likely have to declare the receipt of the points as income, at the same rate.

So unless you are intent on donating all of your points, you're probably money ahead to skip the tax receipt.