How do I amend my federal tax return for this year? I forgot to add a 1099-int that changed the amount I owe.

[userdj9281]

I read online instructions for this but it didn't say how to actually submit the ammended update.

[DoninGA]

If the return is accepted you will have to amend your original tax return. An amended return, Form 1040-X, can only be printed and mailed to the IRS if the original tax return was not e-filed. The IRS will take up to 20 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 for amending a tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...

[MonikaK1]

As @DoninGA stated, you will need to confirm that your original return was processed before amending it. 

See this article and this one for more information about filing an amended return with TurboTax. Once you start the process, follow the on-screen instructions.

@userdj9281