Do i need to show my estimated taxes in paid in 2020. if so where do i need to file this. will there be an additional cost?

[robert-faas]

also, i already filed

[MaryM428]

If you did not include your estimated taxes on your 2020 return, you will file an amend and include the amounts paid.  There will be no additional charge to file the amend.

Amend will be available in TurboTax on March 25, 2021.

When you amend your return, you follow these steps to enter the estimated taxes paid:

1. With your return open, search for the term estimated tax payments.
2. Select the Jump to link.
3. Choose Start next to the type of estimated tax payment you'd like to enter.
4. Enter the amount of estimated tax you paid at each of the quarterly due dates
    

Here is the IRS information on estimated taxes.

[VolvoGirl]

If you sent in the quarterly estimated payments for 2020 I would wait until the IRS sends your refund.  They may add them in for you.  Wait and see.