Yes, you should definitely amend your 2021 return before working on 2022. You want to begin 2022 with the amended information.
When you first open TurboTax Business for 2021, be sure you agree to all TurboTax updates. You should be asked about amending your return in the first few screens after opening last year's file. Follow the prompts about amending. Then go to the California tab and review your answers about the PPP Loan. Since the state tax law has changed, you should be able to exclude that income from state tax.
Be sure to save the 2021 TurboTax file with a new name (add "amended" perhaps). When you are finished and have filed the amended return, open that file in TurboTax 2022 so you start with the updated information.
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