Paid additional 2020 state taxes in 2021 not included in 2020 filing. where can I deduct in my 2021 filing?

Please follow these steps to enter the 2020 state taxes paid in 2021:

1. Click on "Search" in the top right and enter "estimated tax payments"
2. Click the "Jump to" link
3. Scroll down to "Other Income Taxes Paid in 2021"
4. Choose "Start" next to "Balance due on your 2020 state taxes paid in 2021"
5. Enter the amount of tax you paid

Good and clear steps.