You can technically amend your return once it's been accepted by the IRS -- you don 't have to wait for your refund.
Ideally, though, you'll wait to file your amended return until you get the refund from your original return. That's because, even if your original return has been accepted by the IRS, it's still possible that the IRS could change your refund or balance due on that return. And since your amended return uses figures from your original return in its computation, the balance due or refund on your amended return could be figured incorrectly.
It's really your call.
Please see the TurboTax Help article "How to amend (change or correct) a return you already filed" for instruction on how to amend your previously-filed tax return.
[Edited 03|18|2020 12:12 am]
