I'm not aware of a private member's bill that has received royal assent and then shortly thereafter.... Private members' bills amending the tax act and receiving royal assent are not terribly common. This is the first one I can think of that has amended the Income Tax Act.
My colleague Miodrag, I think, might have a better recollection of one with slightly different facts. A government bill was passed that provided that a private member's bill would not come into force, but that's a slightly different situation.