I just e-filed and forgot to upload my 1099-B forms. Can I still do it through Turbo Tax?

You cannot change or add anything on the return that you just e-filed, nor can you stop it.  It is too late, just like when you put an envelope in a US mailbox on the corner.

If you left out a W-2, a 1099G, or a dependent, or a 1099 etc…DO NOT change your return while it is “pending.”  The changes will go nowhere.

Now you have to wait until the IRS either rejects or accepts your return.  If your return is rejected, you will be able to go into your account and make the necessary changes to your tax return and re-submit your return. 

 If the IRS accepts your return, however, then you have to wait longer until it has been fully processed and you have received your refund.  THEN you can prepare an amended tax return and e-file or mail  it in. You have to be able to work from that return exactly the way it was when it was e-filed originally.  You will need to use a form called a 1040X.

  Meanwhile, DO NOT go in and start changing anything on your return in the system, or you will make a mess for yourself.  Sit tight and wait until you see what the IRS does with the return you just e-filed

Did you forget to enter that information on the return ???   If so you must WAIT for the IRS to accept or reject the return you JUST filed.  

• If it is Rejected you will be able to correct the rejection error and make the needed corrections and refile the return.  

• If it is Accepted you will have to wait and file an amended tax return:
• If you're getting a refund wait until the refund comes in.
• If you owe money wait at least two weeks before filing the amended return.  (This is so that the IRS has time to process the original return.)

To amend a return 

Some quick ground rules:

1. Be sure the original return was filed and accepted.
2. DO NOT go back into the return or change anything before you start the amendment process.
3. Gather everything you need before you start.
4. Complete the entire amendment process before you log out.
5. Starting with 2020 tax returns you can E-File a 1040-X amended tax return.  All prior years must be printed and mailed.

 You can correct a return that you've already filed and had accepted.  Select the year that applies and use this guide to proceed.

Select your tax year for amending instructions:

• 2020
• 2019
• 2018
• 2017

For additional information please refer to  How to Amend