Yes, when you start the amend process, the refund that is
shown in TurboTax is reset to zero.
You will still get the original refund if you were due
one based on your original tax return. The amended return will show the
difference you owe, or that you will get back as a refund. If you are due an
additional refund based on the amended return, it will come separately in the
form of a paper check.
