You cannot prepare a 2020 return using the online program. Online is only for 2021 returns.
Do you mean you did not file a tax return for 2020 at all---- or just that you filed and did not claim your dependent? If you did not file 2020 at all, you can use the CD/download to do so. If you asking how to add a dependent to a 2020 return you filed last year, you need to amend that return.
If you did not file 2020 at all:
Online preparation and e-filing for 2018 and 2019 and 2020 is permanently closed.
To file a return for a prior tax year
If you need to prepare a return for 2018, 2019 or 2020 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.
https://ttlc.intuit.com/community/state-taxes/help/how-do-i-contact-my-state-department-of-revenue/0...
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 need to amend 2020:
Select your tax year for amending instructions:
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
