Ok ... so you just filed the 2018 information on the 2019 program ??? That is a big mistake ... so here are your steps.
1) If the return is rejected ... thank your lucky stars !!! You can now use the 2019 program to file the 2019 return if you need to file one ... simply remove the 2018 info and replace it with the 2019 info ... do NOT use the amendment process. If you used the free version then you may wish to start over from scratch in a new account if the return is complicated.
2) If the return is accepted for processing ... you will need to WAIT a long long time for the IRS to decide what it is going to do with the incorrect return. If they actually process it then you WILL need to amend the 2019 return to correct the information on the return if you will file a 2019 return. But more likely they will NOT process the return since they will not be able to match your info with what was sent in by your employer and they will send it back or mail a notice for clarification ... at that time you can let them know of the error.
3) 2018 ... it still must be filed on 2018 forms ... this can be mailed in now ... you do not need to wait for the incorrectly filed return to process. As you already learned you cannot use any online options for a prior year return ...
You can only buy the download for prior years. You have to buy a separate program for each year. They only sell the last 3 years. You need a full Windows or Mac computer to install it on. Buy the download here
https://turbotax.intuit.com/personal-taxes/past-years-products/
You have to print and mail prior year returns. When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return. Don’t forget state.
Important! Mail Federal and State in separate envelopes and mail each year in separate envelopes.
If you are getting a refund, there is not a penalty for filing past the deadline. You have 3 years to file for a refund. If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.
How to file a prior year
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-prepare-a-prior-year-tax-return/00/25...
Or If you have a simple return You can fill out the blank forms for free.
Here is the IRS 2018 Form 1040
https://www.irs.gov/pub/irs-prior/f1040--2018.pdf
And 2018 Instructions https://www.irs.gov/pub/irs-prior/i1040gi--2018.pdf
2018 Tax and EIC Tables https://www.irs.gov/pub/irs-prior/i1040tt--2018.pdf
IRS 2018 Schedules 1 thru 6 (only if needed)
Sch 1 : https://www.irs.gov/pub/irs-prior/f1040s1--2018.pdf
Sch 2 : https://www.irs.gov/pub/irs-prior/f1040s2--2018.pdf
Sch 3 : https://www.irs.gov/pub/irs-prior/f1040s3--2018.pdf
Sch 4 : https://www.irs.gov/pub/irs-prior/f1040s4--2018.pdf
Sch 5 : https://www.irs.gov/pub/irs-prior/f1040s5--2018.pdf
Sch 6 : https://www.irs.gov/pub/irs-prior/f1040s6--2018.pdf
