I am single and only have $6000 income. I just filed the return to claim the tax withheld. I got a another W2 after I filed the return, it would only add $400 to my total income. Do I have to amend the return? Thank you.
Yes, you will need to amend to add that W-2. The IRS gets copies of all of your W-2s and other tax forms and will be looking for that income to be included on your return. See here for more details Do I need to amend?
So if you already filed, you'll need to wait until the IRS either accepts or rejects your return before you can add anything else.
If they reject it, you just add that W-2 and re-submit the return.
If they accept it, you will need to wait until they have fully processed the return and you have received your refund (or paid taxes due) and then amend that return to add that W-2.
Amended returns must be printed and mailed. They cannot be e-filed per IRS regulations.
Once you mail an amended return, it can take up to 3 weeks before it shows up in the IRS's system. So give it that amount of time before you start checking for any updates on it. After 3 weeks, you can go here Where’s My Amended Return? to check the status of it.