What I do not know is why did not Turbo Tax flag this as an error. I reran this again today and nothing was flagged as an error.
TurboTax does not flag it as an error because TurboTax has no way of knowing that it's an error. TurboTax has to rely on you to enter information accurately. If you enter your real estate tax in two different places, TurboTax has to assume that that's how much you paid. It cannot assume that having the same amount in two different places is an error. You have to look over your tax return before you file it. If you had seen the $8,244 real estate tax amount on the TurboTax screen or on Schedule A before you filed the return, I'm sure you would have realized that it was wrong and corrected it.
hiow does one ammend this return>
Go to the following link for instructions to amend a 2017 tax return that you filed with the CD or download TurboTax software.
Before you start to amend the return, save a copy of the .tax2017 data file with a different name. Use one copy to amend the return, and keep the other copy as a backup of the original return.
An amended return has to be filed on a special form, Form 1040X. It cannot be e-filed. You have to print it, sign it, and file it by mail. It takes the IRS up to 16 weeks to process an amended return.