If you filed an amended return, you should have started out with a balance of zero. That would indicate that TurboTax expected that you had already paid the $300, so your balance is zero. If that is true, you should get a refund of $1,200, which accounts for the $300 you paid.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
