Should you amend your prior year tax return? It all depends upon what is left off.
Generally, you should correct your tax return:
- Because you want to minimize any additional tax and penalty or interest that you might owe, or
- To receive a refund of income tax withheld.
If your return has been transmitted and accepted by the IRS, you must amend your Federal 1040 tax return.
If you used TurboTax Online, simply log in to the account that was used to create the original tax return and select “Amend a return that was filed and accepted.”
If you used the CD/download product, sign back into your return and select “Amend a filed return.”
You must file a separate Form 1040-X for each tax return you are amending.
See also this TurboTax Help.