Then you will have to file an amended 2020 tax return after the IRS accepts and processes your tax return.
The IRS will not be accepting or rejecting any 2020 tax returns until February 12, 2020
An amended return, Form 1040X, can only be printed and mailed to the IRS, it cannot be e-filed. The IRS will take up to 16 weeks or longer to process an amended tax return.
Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed by the IRS.
See this TurboTax support FAQ on amending a tax return originally completed and filed using the 2020 TurboTax online editions - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/01/27577
