You must wait until your tax return is pulled from the TurboTax servers by the IRS on Jan. 28 or shortly thereafter. It will be accepted or rejected by the IRS. If it is rejected, you can redo the information on the return and replace it with your 2018 information and resubmit it as a 2018 return.
If the return you mistakenly efiled with 2017 information is accepted by the IRS, you must wait until it is processed and you get a refund. You can then start an amended return to fix everything by entering your 2018 information. The amended return is form 1040X that must be prepared, printed, signed and mailed. It cannot be efiled. Do not change anything on your accepted return until you start the amended return. The 1040X may not be available in TurboTax until late February or March. It takes the IRS about 16 weeks to process an amended return.
Regardless of whether your mistakenly submitted return is accepted or rejected, you can prepare, print and mail a 2017 tax return using the prior year program that you can buy from TurboTax at this link: https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2017 return cannot be efiled. It must be mailed.
