Wait until your first return has been processed by the IRS. If
you're amending to claim more money, the IRS says to wait until you've received
your original refund before filing an amendment.
Once you've
received your original refund, feel free to cash or spend it while your
amendment gets processed (this can take 12–16 weeks).
Three weeks
after you mailed your amendment, you can start tracking its progress at the
IRS Where's My Amended Return? site.
Additional information:
How to amend (change or correct) a return you already filed
