Sorry, Online for 2019 and prior is closed now so you can not start a new 2019 or 2018 return or finish one. Online is only for 2020. Oct 15, was the last day to efile. 2019 is now the prior year. If you entered 2019 into the 2020 online version you should clear out your online return so you can use it for 2020.
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-clear-and-start-over-in-turbotax-online/00/26444
Did you start an Online return? How to finish a prior year online return
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-started-in-turbotax-online/00/26322
Or How to file a prior year
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-prepare-a-prior-year-tax-return/00/25984
You can only buy the download for prior years. You have to buy a separate program for each year. They only sell the last 3 years. You need a full Windows or Mac computer to install it on. Buy the download here
https://turbotax.intuit.com/personal-taxes/past-years-products/
You have to print and mail prior year returns. 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 received the return. Don’t forget state.
Important! Mail Federal and State in separate envelopes and mail each year in separate envelopes.
If you are getting a refund, there is not a penalty for filing past the deadline. You have 3 years to file for a refund. 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.
If you want to file for free you can fill out the forms by hand. Here are some basic forms…..
Here is the IRS 2019 Form 1040
https://www.irs.gov/pub/irs-prior/f1040--2019.pdf
or if you want bigger type use 1040SR for Seniors,
https://www.irs.gov/pub/irs-prior/f1040s--2019.pdf
And 2019 Instructions https://www.irs.gov/pub/irs-prior/i1040gi--2019.pdf
2019 Tax and EIC Tables
https://www.irs.gov/pub/irs-prior/i1040tt--2019.pdf
Sch 1 : https://www.irs.gov/pub/irs-prior/f1040s1--2019.pdf
Sch 2 : https://www.irs.gov/pub/irs-prior/f1040s2--2019.pdf
Sch 3 : https://www.irs.gov/pub/irs-prior/f1040s3--2019.pdf
Then when you do file 2020 enter 0 for the 2019 AGI since you are filing 2019 late.
Its strange because the site says you can file prior year for free
Downloads are available for tax prep, however, you are NOT able to E-file the previous year return. Although you may use TurboTax for back filing, you will still need to print and mail file.
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/
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.