Corrected W2

If your change results in a balance due to the IRS, you will need to file an Amended Return (1040X).

 

You won't be able to amend your tax return until the IRS releases the 1040-X Amendment form for 2019. The IRS estimate for issuing the 1040X form is mid February.

 

Additionally, make sure that your 2019 return was accepted in TurboTax Online or paper-filed through the mail.  

 

To prepare an amended return through TurboTax, follow these steps:

1. Sign in to TurboTax.
2. Scroll down to Your tax return & documents (you may need to select Show), select 2019 and then Amend (change) return.
3. Select Amend using TurboTax Online.
4. Carefully follow the instructions. Don't worry if your refund changes to $0. This is normal on amended returns.
5. When finished, we'll give you instructions for printing and mailing your amended return as amendments can't be e-filed.

Do you need to file the amended return if the correction to the W2 results in a small addition to your refund?  Can you decide not to file the amended return because the effort to do so will greatly exceed the benefit to you?

No if the tax liability goes down (larger refund) then it is up to you to decide if you want to file or not for that refund.  You have 3 years after your filing deadline to file an amendment for a refund.