You do not amend a return that was never filed in the first place. Amending is a special process one only uses for a return that has been filed with mistakes that has been fully processed by the IRS--that is not your situation, You need to file a 2016 return that was never filed at all.
Either your 2016 return was not filed or your return was rejected and you did not notice and follow up to re-file it. If you used TurboTax you can look for the return in your account. It will have to be printed signed and mailed. It cannot be e-filed.
If you just flat out did not prepare a 2016 return then you can still do so:
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.
How do I finish a prior-year return that I started in TurboTax Online?
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. You can buy any version. All the Desktop programs have the same forms. You just get more help and guidance in the higher versions. Buy the download here
If you have a simple return, you can fill out the blank forms by hand for free.
Here are some blank forms & instructions for 2016
2016 Tax Tables https://www.irs.gov/pub/irs-prior/i1040tt--2016.pdf
Publication 17 Tax Guide for 2016 https://www.irs.gov/pub/irs-prior/p17--2016.pdf
Prior year returns can only be printed and mailed. 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.
And don't forget state.