I eFiled very early (Feb 6, 2019) . Now, after turbotax updates, the calculation results in a larger refund. Will IRS catch this and send me the difference, or should I file amended return?
You will need to amend if you are due a larger refund due to a tax law change or software update. See the link below for instructions. If the IRS has already processed your return, then they do not have the updated information (1040X) needed to issue you the difference.