Is it bad to add another w-2 after submitting my return

Yes, you'll have to amend your tax return.

You must report  all income to the IRS, that include the W-2 that wasn't posted.

If you want to make changes, or add a document to a tax return that has already been submitted you should follow these guidelines.

• You must first wait until the initial return is completely processed.
• You will have to use the same TurboTax account that you used for the original tax return.
• Once you begin your amendment, you'll see your original return. 
  • The refund calculator will start new at $0 and only reflect the changes in the refund or tax due
  • Only make changes to the areas of your return that need amending.
• You have three years from the date you filed your return or two years after you paid the tax due (whichever is later) to file an amendment

Sign in to TurboTax

1. On the home screen, scroll down to Your tax returns & documents and 
2. select the year you want to amend
3. Select Amend (change) return, then 
4. Amend using TurboTax Online
   1. If you're told to amend your return via TurboTax Desktop, follow the steps for TurboTax CD/Download below instead.
5. On the screen OK, let's get a kickstart on your amended return, select the reason(s) you're amending and Continue.
6. When you reach Here's the info for your amended federal return, select Start next to the info you need to change.
7. Continue through the screens, make the changes you need to make, and carefully answer the remaining questions to finish amending your return.
    

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