TT Online is only good for 2020. You would have to purchase and download the desktop software for each of the prior years, and file by mail. TT currently supports 2017, 2018 and 2019.
TurboTax® 2017 Tax Software for Filing Past Years’ Taxes, Prior Year Tax Preparation (intuit.com)
TurboTax® 2018 Tax Software for Filing Past Years’ Taxes, Prior Year Tax Preparation (intuit.com)
TurboTax® 2019 Tax Software for Filing Past Years’ Taxes, Prior Year Tax Preparation (intuit.com)
Federal refunds for earlier years are time-barred, but some states have longer Statutes of Limitations.
The link that was given to me for 2017, 2018, and 2019 Biz tax returns went dead after I downloaded the 2018 tax returns. I still need 2019.
Did you pay for each download----2018 and 2019?
https://turbotax.intuit.com/personal-taxes/past-years-products/
Access your downloads here
https://shop.turbotax.intuit.com/commerce/account/secure/login.jsp?pagecontext=download
https://ttlc.intuit.com/community/tax-topics/help/activating-turbotax-cd-download-software/00/852971
To find your license code:
https://ttlc.intuit.com/community/tax-topics/help/i-can-t-find-my-license-code/01/852973
Note: There is not a license code for the 2018 software. They began to use license codes with 2019 software and beyond. The 2019 license code will be a 14 digit code.