If I set up a joint account using my ss number with my daughter, how is that taxed when I die?

If she draws a check for 50M to buy a car for herself, do I pay a gift tax on it (Minus the yearly allowance)?:) ]

The money is part of your estate; it just will not be probated.

Yes, because it IS considered a gift!

As ATE says, the value of the bank account will be included in your estate. During your life, there will be no gift unless and until your daughter withdraws cash from the account. To the extent that you gift her more than $12,000 in one year, they will be taxable gifts and a gift tax return will be due. You may also owe state gift tax.