After you file

You do not amend a tax return that has never been filed.    Amending is a process to use if you filed the tax return and the IRS processed it, and then you discovered a mistake, etc.   Amending is NOT what you do for never-filed tax return.

If you have past year returns that you need to prepare and file:

The current online program can only be used for a 2020 return--no other year.  And if you did not file a 2019 return you will have trouble e-filing 2020.  When it asks for your 2019 AGI try using zero.  If zero does not work then you have to print, sign and mail 2020.

Online preparation and e-filing for 2017, 2018 and 2019 is permanently closed.

To file a return for a prior tax year

 If you need to prepare a return for 2017, 2018, or 2019 you can purchase and download desktop software to do it, then print, sign,  and mail the return(s)

https://turbotax.intuit.com/personal-taxes/past-years-products/

You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.

Remember to prepare your state return as well—if you live in a state that has a state income tax.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.

Note:  The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac.  It cannot be used on a mobile device.

If you are getting a refund, there is not a penalty for filing past the deadline.  If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.

Or.....do you mean you filed those returns but used some other software and they need to be amended to correct a mistake?

CAN I USE TURBOTAX TO AMEND IF THE RETURN WAS PREPARED SOMEWHERE ELSE?

If you did not use TurboTax to prepare your tax return, it is possible to amend the return using TurboTax but it will really be a pain.  It would be better to use the software or service used to file originally.  If a paid preparer made a mistake on your tax return, that tax preparer should do the amended return for you at no charge.

In order to use TurboTax to amend your return, you need to purchase the desktop software for the tax year and re-create the return EXACTLY as it appeared when it was filed with the IRS/states.  Every line has to be the same.  Then you have to "trick" the software into thinking you filed by saying you will mail the return. (but do not mail it)   AFTER that, you use the software to prepare a Form 1040X, which has to be printed, signed and mailed to the IRS.  It takes the IRS about 3-4 months to process an amended return