you need to either buy the desktop software for each year or get the forms from the IRS website and prepare your returns manually. online preparation for 2017 and 2018 is closed. even with the desktop software, you'll need to paper file the returns since e-filing them is closed. mail each year in a different envelope and if you are due a refund expect a wait that will exceed 4 months. use a method where you can track receipt. be sure to follow TT filing instructions including the need to attach any forms with withholding.
You have TWO returns to file. Do not try to combine them in any way--do not even mail them in the same envelope.
To file a return for a prior tax year
If you need to prepare a return for 2016, 2017, or 2018 you can purchase and download desktop software to do it, then print, sign, and mail the return(s)
Remember to prepare your state return as well—if you live in a state that has a state income tax.
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/state received the return.
Note: The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac. It cannot be used on a mobile device.
If you are getting a refund, there is not a penalty for filing past the deadline. 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.