Deduction

if paid in 2020 it's a 2020 item. if paid in 2021 it's a 2021 item.  however if you put tr bill on a credit card in 2020 that you didn't pay until 2021 or may still owe, it goes on 2020

No, if you initially had the expense in 2020, you must amend your 2020 return to include it.

Amending a 2020, 2019, or 2018 state return is very similar to amending a prior-year federal return. Here are some tips:

• If you're amending a 2020 return you originally prepared in TurboTax Online, you can amend it online by signing in to TurboTax.
• Be sure to download and install the appropriate state software.
  • For example, to amend your 2018 California return, download and install the 2018 TurboTax California state software.
  • The amendment software that we offer to prior-year TurboTax Online customers includes 1 free state download. Contact us if you need to download additional states that you paid for when you originally filed.
• TurboTax state programs vary in amendment instructions, but you'll either find the amendment option at the beginning or close to the end.
• The state program doesn't function as a standalone product. Even if you only need to amend your state return (not the federal), install the federal program for the corresponding tax year.
• If the change originates on the federal return (for example, you need to add or change your W-2 information), amend your federal return before amending your state. This carries the information over into your state return.