If you filed using TurboTax, amending is free.
Before you can correct (amend your return), you will need to wait until your return has been accepted and processed by the IRS. It generally takes the IRS 10-21 days to process a
return, but it can take longer in certain circumstances. TurboTax will
prompt you to amend your state return when you redo your Federal
return. If the error affects both returns, you will need to amend your state return as well.
Here's how to
Amend
My Return in TurboTax.