Did you file the 2020 tax return and was it accepted by the IRS? If so, then you need to amend the 2020 tax return to add the 2020 Form 1099-B you received.
See this TurboTax support FAQ for amending a 2020 tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-2020-return/L3XdA1Pw8_U...
A 2020 amended tax return can only be printed and mailed, it cannot be e-filed.
If you have a capital loss carryover based on the 2020 amended return then you report the carryover on the 2021 tax return, assuming you have not yet filed the 2021 return.
For a capital loss carryover -
- Click on Federal Taxes (Personal using Home and Business)
- Click on Wages and Income (Personal Income using Home and Business)
- Click on I'll choose what I work on (if shown)
- Under Investment Income
- On Capital Loss Carryover, click the start or update button
Or enter capital loss carryover in the Search box located in the upper right of the program screen. Click on Jump to capital loss carryover
If you have filed the 2021 return then you should wait for the 2020 amended return to be processed before amending the 2021 tax return.
NOTE - It may take up to a year before the IRS completes the processing of an amended tax return.
