I need to amend my return, but I have already received a check from IRS (they approved my return that I need to amend). Should I cash out this check and then amend my return, or should I dispose this check and wait for a check from an amended return?
The amended return Form 1040x has a different calculation for the `Refund or Amount You Owe' section than the original 1040, you use the amount you owed or amount overpaid from the original return to offset the impact of the amended return. This calculation assumes the refund/payment has been made already.
So deposit your refund check, then file the amended return. I suggest filing sooner rather than later in case you owe (unlikely to be penalized unless it's significant/fraudulent), but sooner is better anyway.
According to TurboTax:
Of course. In fact, the government doesn't want you to amend until you've already gotten your tax refund.
You're free to cash your refund check or spend it once you have it. You don't need to wait for your amendment to finish processing, which can take another 3-4 months.
If you owe money after amending, you'll just include payment with your mailed amendment form.
And if your amendment results in a second refund, you'll get a check for the additional amount.
So yes, you can cash out this check and then amend your return. If you end up owing money, you'll just pay it when you file your amended returns: