Correct.
Take a look at the 2017 form 1120. It says "tax year beginning ____2017..." That is why TT will not take a 2016 date in that first field.
<a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-pdf/f1120.pdf">https://www.irs.gov/pub/irs-pdf/f1120.pdf</a>
And here is the 2016 form 1120
<a rel="nofollow" target="_blank" href="
https://www.irs.gov/pub/irs-prior/f1120--2016.pdf">https://www.irs.gov/pub/irs-prior/f1120--2016.pdf...>
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
