In box 12a I entered code a instead of code dd. It lowered my refund by the amount I entered. Do I need to file an amended return to change this?

I thought that where it said 12a was the code but it was meaning box 12a

After you file

It's possible the IRS would eventually catch this, but not for several months if at all.  Wait until your original return is accepted, processed and your refund is paid.  Then you can prepare an amended return.

If your return has not been accepted yet, and comes back rejected for some reason, that is the same as never being filed.  You can fix this error, as well as any other errors, and re-transmit your return (this is not an amended return). 

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